The accident happened ______ a freezing winter morning.
| A．on | B．in | C．at | D．since |
—Did you see him yesterday?
—No, when I got to the airport, he a taxi for home.
| A．has taken | B．had taken | C．will take | D．would take |
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 |