1 . 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）

2 . Most characters in movies are i________（虚构的）.

3 . “I cannot i________ just how hard the Chinese doctors and nurses have worked,” he said. (根据首字母单词拼写）

4 . Do you_____（设想.想象）travelling to the moon to spend your summer holiday? （根据汉语提示单词拼写）