1．—What’s that noise?
—Oh, I forgot to tell you．The new machines ____________ （检测）．（test）
2．I didn't know_________（他说了些什么） to his teacher, （say）
3．When Mark opened the door, he saw a woman_________ （站在那里）．He has never seen her before, （stand）
4．Not until we know more about the environment _________ （我们将能够）improve the situation, （able）
5．When was it ________ （他们到达） the city of Johannesburg? （arrive）
