Grammatical range and accuracy is a quarter of your Writing and Speaking scores, and it is the criterion students most often try to fix with quantity — long sentences, more clauses, more commas. Range means variety used accurately. Five structures will give you most of it.
One. The relative clause that adds information. "Students who move abroad for a master's often underestimate living costs." Note: no comma when the clause defines which students. A comma changes the meaning to "all students, and by the way…".
Two. The concessive clause. "Although online courses are cheaper, they demand more self-discipline." One idea placed against another in a single sentence, which is exactly what a discussion essay is made of. Alternatives: while, even though, despite the fact that.
Three. The conditional, used for consequence. "If cities continue to grow at this rate, existing transport networks will not cope." The second conditional for hypotheticals — "if governments required students to return, fewer would apply" — is worth having as well, and it is the one most students avoid.
Four. The passive, where the actor does not matter. "A chemical is added to make the fine particles clump together." Essential in Task 1 process questions, and quietly useful elsewhere: "the policy was introduced in 2015". Do not overuse it in Task 2, where naming who acts is usually stronger.
Five. The noun phrase that compresses a whole clause. "The rising cost of urban housing has pushed families further out." Compare: "Because the cost of housing in cities is rising, families have been pushed further out." Both are correct; the first is denser, and a script that can do both reads as controlled.
Now the accuracy half, because range without it scores nothing. The three errors that cost Indian students the most marks in this test are articles (a/an/the before countable singulars), subject–verb agreement across a long subject ("the number of students has risen", not have), and plural agreement ("many researchers argue", not "many researcher argues"). None is hard. All are habitual, which means they are fixed by proofreading with a specific list rather than by reading the essay again and hoping.