2 . 想象一下，独自在家时，你可以与数百人一起引吭高歌。
________ together with hundreds of other people while you are at home alone.

3 . In court, the witness were required to distinguish the difference between what he heard and saw and what he i_______.(根据首字母单词拼写)

4 . It has four Roll-Royce Merlin engines, but the group will need to have only three of them rebuilt. ____________ when they broke open the packing cases and found that the fourth engine was sweet as honey-still in perfect condition.（根据句意填空）