用所给动词的适当形式填空

1. It's required that you____(start) before seven o'clock.

2. If only I_______(get)a good job in that company now.

3. The doctor ordered that she________(stay) in bed for a few days.

4. It's high time we_______(leave) for our hometown.

5. He speaks English as if he_________(study) it in England before．

在850nm窗口，光纤即可以用于单模传输，又可以用于多模传输。 （）