1 . It suddenly ________ (occur) to him that he had an important meeting to attend the next morning. (所给词的适当形式填空)

3 . The black car drove away from them and ____________(消失). (根据汉语提示单词拼写)

4 . The crash ________ (occur) when the crew shut down the wrong engine.(所给词的适当形式填空)

5 . She took her son, ran out of the house, _______ him in the car and drove quickly to the nearest doctor’s office.

A．putting

B．put

C．to put

D．having put

6 . He ________ (sharpen) his knife in order that he cut meat easily . （所给词的适当形式填空）