DET Grammar Rules That Decide Your Score

The DET tests grammar in a specific way: through Read and Complete and Fill in the Blanks, where you supply missing letters or words, and through the accuracy of the writing and speaking you produce. There is no grammar section, which is why grammar work has to be aimed at those tasks rather than studied in general.

Each rule below is a decision you can make in the exam, with the task it applies to.

Want to ACE the Duolingo English Test (DET) And Reach Your Goals? Get Your FREE Lume Account Today to Unlock… ✅ 10,000+ PRACTICE QUESTIONS with detailed answers ✅ FREE MOCK TESTS with fast & accurate AI scoring ✅ Get BETTER SCORES with a PERSONALIZED study plan GET YOUR FREE ACCOUNT NOW (Limited seats available!)

Key Takeaways

• DET grammar is tested through Read and Complete, Fill in the Blanks, and accuracy in your own writing and speaking.
• Read and Complete gives you the first letters of a word — grammar plus context tells you the rest.
• Word form, articles, prepositions and verb agreement produce most of the recoverable marks.
• DET items carry partial credit, so a partially completed word or sentence still scores.
• The same rules let you reconstruct function words in Listen and Type.

Which tasks grammar affects

Task	How grammar matters	Subscore
Read and Complete	You supply missing letters; grammar narrows the word	Reading
Fill in the Blanks	You choose the missing letters of a word in context	Reading
Listen and Type	Grammar reconstructs function words you did not catch	Listening
Write About the Photo	Accuracy and range in your own sentences	Writing
Interactive Writing	Accuracy and range across a longer response	Writing
Writing Sample	Accuracy and range in an extended piece	Writing
Speak About the Photo, Read Then Speak, Interactive Speaking	Accuracy in spoken production	Speaking

Rule 1: word form is decided by position

Position	Needs	Example
After an article, nothing after it	Noun	the decision
Between article and noun	Adjective	the final decision
After a complete clause	Adverb	arrived early
After a linking verb (be, seem, look, become)	Adjective	seems reasonable
After a subject with no other verb	Finite verb	The train arrived
After a preposition	Noun or gerund	without warning / after leaving

In Read and Complete this is the first thing to apply: the position tells you the part of speech before the visible letters tell you the word.

Rule 2: what the visible letters plus grammar give you

Read and Complete shows the first letters of a word and asks you to finish it. Position narrows the part of speech; the letters narrow the word.

What you see	Position tells you	Likely word
“the dec___ was announced”	Noun, singular, subject	decision
“had been rec___ by the office”	Past participle, passive	received
“the app___ deadline”	Noun or adjective before a noun	application
“arrived unex___”	Adverb after a complete clause	unexpectedly
“is ent___ to a refund”	Past participle plus “to”	entitled
“nei___ of the two proposals”	Quantifier before “of the two”	neither

Rule 3: articles

Situation	Article	Example
First mention, countable singular	a / an	I received a letter.
Second mention of the same thing	the	The letter arrived late.
Unique or already identified	the	The deadline has changed.
General plural	No article	Deadlines are often extended.
Uncountable, general	No article	Information was provided.
Job title after “as”	a / an	She works as a nurse.
Superlative	the	the largest collection

Article errors are the most frequent accuracy loss in DET writing tasks, and this table covers nearly all of them.

Rule 4: subject-verb agreement

Structure	Verb agrees with	Example
Subject plus prepositional phrase	The subject	The list of names is attached.
Each / every / either / neither	Singular	Every student receives a reply.
A number of	Plural	A number of people have applied.
The number of	Singular	The number of applications has risen.
Either A or B	The nearer noun	Either the tutors or the head signs.
There is / there are	What follows it	There are several crates.

The last row matters in Write About the Photo, where “there is” and “there are” appear in almost every answer.

Rule 5: tense and time markers

Marker	Tense	Example
yesterday, last week, in 2019, ago	Past simple	The shop closed in 2019.
since, for, so far, already, recently	Present perfect	She has worked here for eleven years.
currently, at the moment, right now	Present continuous	They are waiting for a bus.
every day, usually, generally	Present simple	The bus runs every twenty minutes.
by + future time, next week	Future or future perfect	It will have arrived by Friday.
before + past event	Past perfect	The equipment had been faulty for weeks.

In Write About the Photo the default is present continuous for actions and present simple for states. Mixing in a past tense without reason is a common error.

Rule 6: prepositions

Preposition	Use	Examples
in	Months, years, longer periods, enclosed spaces	in March, in 2024, in the room
on	Days, dates, surfaces	on Monday, on 14 April, on the table
at	Clock times, points, addresses	at 9:00, at the entrance
by	Deadline	Submit by Friday.
until	Continuing up to a point	Open until midnight.
within	Inside a period	within thirty days
during	Throughout an event	during the lecture
for	Length of time	for eleven years
since	Start point with perfect tenses	since March

Position preposition	Use in photo tasks
next to / beside	Immediately adjacent
behind / in front of	Depth relative to the viewer
above / below	Vertical, not touching
on the left / on the right	Side of the frame
in the foreground / background	Distance from the viewer

Rule 7: countable and uncountable

Noun type	Use	Never
Countable plural	many, few, several, a number of	much, an amount of
Uncountable	much, little, a great deal of	many, few, a number of
Either	some, any, a lot of, plenty of	—
Common uncountables	information, research, advice, equipment, furniture, luggage, weather	Never “informations”, “advices”, “equipments”

Rule 8: participles as modifiers

Form	Meaning	Example
-ing	The noun does it	the approaching bus
-ed	It is done to the noun	the covered shelter
-ing after a noun	Reduced relative clause	a woman wearing an apron
-ed after a noun	Passive reduced clause	a notebook covered in handwriting

The last two rows are the most useful structures in Write About the Photo: they add detail without a new sentence, which is exactly what a 60-second window needs.

Rule 9: comparatives

Structure	Form	Example
“than” in the sentence	Comparative	much wider than before
Three or more items	Superlative with “the”	the largest collection
Equality	as + base + as	as busy as usual
Intensifier	much / far / slightly / considerably	considerably milder
Preference	would rather + bare infinitive	I would rather walk.

“Very” cannot modify a comparative. “Very wider” is always wrong.

Rule 10: reconstructing function words in Listen and Type

What you heard	Reconstruct as
“been” with no auxiliary	has been or have been — check the subject
A noun with no article, first mention	a or an
A verb with no ending on a plural subject	No -s
A subordinate clause first	Comma before the main clause
A comparative adjective	“than” follows
A time expression	in, on, at, by — decided by the noun

Decision checklist

1. In Read and Complete, decide the part of speech from the position before looking at the visible letters.
2. Check for a preposition or auxiliary immediately before the gap — it fixes the form.
3. Look for “than” anywhere in the sentence — it forces a comparative.
4. Check whether the noun is countable plural, countable singular or uncountable before choosing a quantifier.
5. In writing tasks, check articles last. They are the most frequent error and the fastest to fix.
6. Always type something. DET gives partial credit and does not penalise a wrong answer more than a blank.

FAQ

Does the Duolingo English Test have a grammar section?

No. Grammar is tested indirectly, through Read and Complete and Fill in the Blanks where you supply missing letters, and through the accuracy of the writing and speaking you produce. That is why grammar study should be aimed at those tasks rather than done in general.

Which grammar matters most for the DET?

Word form, articles, subject-verb agreement, prepositions and participles. Word form and the visible letters together resolve most Read and Complete items, and article errors are the most frequent accuracy loss in the writing tasks.

How does grammar help in Read and Complete?

The position of the gap tells you the part of speech before the letters tell you the word. “had been rec___” must be a past participle, which narrows the candidates far more quickly than guessing from the letters alone.

Is a partially completed answer worth anything?

Yes. DET items carry partial credit and Duolingo states you are not penalised more for an incorrect response than for skipping, so a partly filled word or an incomplete sentence still scores.

Which grammar structures help most in Write About the Photo?

Reduced relative clauses — “a woman wearing an apron”, “a notebook covered in handwriting”. They add detail without a new sentence, which is exactly what a 60-second window needs, and they demonstrate range at the same time.

Do I need to study advanced grammar for a high DET score?

Range matters, but accuracy in the common structures matters more. A response using present continuous, there-are and one subordinate clause correctly scores better than one attempting a conditional inversion and getting it wrong.

Related practice resources

• DET collocation list
• DET Listen and Type practice
• DET Read and Complete practice with answers

Want to ACE the Duolingo English Test (DET) And Reach Your Goals? Get Your FREE Lume Account Today to Unlock… ✅ 10,000+ PRACTICE QUESTIONS with detailed answers ✅ FREE MOCK TESTS with fast & accurate AI scoring ✅ Get BETTER SCORES with a PERSONALIZED study plan GET YOUR FREE ACCOUNT NOW (Limited seats available!)