Question

3. Sarah reached the hall at 9.30 a.m. The meeting began at 9.15 am (The meeting / already/begin/Sarah / reach/hall)
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Answer 1

1) The meeting began when we arrived at the hall. (Wrong)

2) The meeting had begun when we arrived at the hall. (Correct)

The above second sentence is grammatically correct, because if two actions happened in the past, it may be necessary to show which action happened earlier than the other. The Past Perfect is mainly used in such situations. The Simple Past is used in one clause and the Past Perfect in the other; as,

The meeting had begun when we arrived at the hall.

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