He speaks too quickly_________.
| A．understand | B．write them down |
| C．to understand | D．and write |
The old scientist devoted most of his time ___________ the space science.
| A．develop | B．to developing | C．to develop | D．developing |
_________good advice! It’s so helpful to us.
| A．How | B．How a | C．What | D．What a |
—Mary was heard_______ just now. What happened?
—John was telling a joke.
| A．cry | B．to cry | C．laugh | D．to laugh |
Even if we are very busy, we should spend ______ doing exercise every day.
| A．some time | B．sometime | C．sometimes | D．some times |
—Is your father a teacher?
—Well, he _______.
| A．used to | B．was used to | C．used to be | D．is used to be |