Grammar: Tense, Voice, Narration, Agreement, Articles, Prepositions
Grammar is the highest-yield part of the paper because the rules are finite and testable. Bihar Board items concentrate on tense, active and passive voice, direct and indirect speech, subject–verb agreement, articles and prepositions, and the marks are almost entirely rule-driven.
Tense
The present perfect takes since with a point of time and for with a duration. In an if-clause, the present tense serves a future meaning ("If it rains, we will stay"). Time clauses with when, before and after take the simple present or simple past, never will.
Voice
Move the object to the subject position, put be in the same tense as the original verb, and add the past participle. Keep the tense unchanged. Use do-support in passive questions and negatives. Only transitive verbs can be made passive.
Narration
Backshift one step when the reporting verb is past (am going → was going). Change first-person pronouns to match the speaker and second-person to match the listener. Shift time and place words: now → then, today → that day, tomorrow → the next day, here → there, this → that. Said becomes told when a listener is named, and reported questions keep statement word order.
Agreement and articles
Each, every, either and neither take a singular verb; "one of the + plural noun" takes a singular verb; "the number of" is singular while "a number of" is plural. Choose a or an by sound, not spelling (an hour, a university). Use the for unique things, superlatives, rivers and mountain ranges, and no article for abstractions used generally.
Worked example
Direct: He said, "I am going to Patna today." Indirect: He said that he was going to Patna that day. Backshift handles am going, pronoun shift handles I, and today becomes that day.
Traps that cost marks
Keeping question inversion in reported questions; forgetting backshift; using by with intransitive verbs; ignoring do-support; and using since for duration.