The boys … football when the teacher entered the class

Analyze the question

The sentence is: "The boys ......... football when the teacher entered the class."

The verb "entered" is in the simple past tense. We need a verb form that fits with it and shows an action already in progress when the teacher came in.

Concept: Past continuous + simple past

When one action was in progress in the past and another action interrupted it, we use:

• Past continuous (was/were + verb-ing) for the longer, ongoing action
• Simple past for the shorter action that interrupted it

Example: She was cooking when the phone rang.

Solution

1. "Entered" is the simple past, so the interrupting action happened in the past.
2. The boys' action was already going on when the teacher entered, so it needs the past continuous.
3. "The boys" is plural, so we use "were".

Checking the options:

• A. are discussing is present continuous, which clashes with "entered" (past).
• B. were discussing is past continuous, which fits.
• C. will be discussing is future continuous, which is wrong because the event is in the past.
• D. will discuss is simple future, which is also wrong.

Note on meaning: "Discussing football" is a bit unusual, since "playing football" would be more natural. Sentence: The boys were discussing football when the teacher entered the class.

Answer: B. were discussing

Exam tip: When you see "when + simple past" in a sentence, look for the past continuous (was/were + -ing) in the other half. Cross out any options in present or future tense immediately.