Qian Xuesen tried many times _________ he found the solution to the puzzle about space technology.
| A．after | B．before | C．since | D．when |
Were it not for the debt, we ______a happy life:
| A．are living | B．would live | C．were living | D．will live |
The stronger the coffee is,______.
| A．the more I like | B．the better I like |
| C．the more better I like it | D．the better I like it |
The form ______in and returned within three weeks.
| A．is to be filled | B．will fill |
| C．is to fill | D．are going to be filled |
"The ground is wet." "Yes, didn't you know? ______for the last 20 minutes."
| A．It's raining | B．It was raining |
| C．It's been raining | D．It has rained |
You look smart in this new jacket. That old one ______ thrown away many years ago.
| A．ought to be | B．ought to have been |
| C．would be | D．would have been |