When I try to understand ____ that prevents so many Americans from being as happy as one might expect, it seems to me that there are two causes.
| A．why does it | B．what does it | C．what it is | D．why it is |
The last thirty years _________ the quick development in almost every field in China.
| A．have searched | B．have released | C．have seen | D．have determined |
The dog, if trained _____, will be made a good watch-dog one day.
| A．hopefully | B．personally | C．usually | D．properly |
It is required that employees in the company have to have a good__________ of English.
| A．request | B．view | C．design | D．command |
We must keep on learning if we want to keep up with the ____ of the changing times.
| A．schedule | B．pace | C．journey | D．transport |
If you are not happy with it, you should say it out. Don’t just ______ in silence.
| A．suffer | B．ignore | C．upset | D．conquer |