So difficult ____ it to live in an English-speaking country that I determined to learn English well.
| A．I have felt | B．have I felt | C．I did feel | D．did I feel |
By the time he was twelve, Edison __________ to make a living by himself.
| A．would begin | B．has begun |
| C．had begun | D．was begun |
As its name indicates, the “American Host Family” program gets American families __________in foreign students' lives in America and offers homes for them.
| A．to involve | B．involving |
| C．involved | D．having involved |
A lot of tall buildings __________ in Shanghai in the past three years.
| A．have set up | B．have been set up |
| C．set up | D．were being set up |
John's success has nothing to do with good luck. It is his hard work __________ has made him what he is today.
| A．why | B．when |
| C．which | D．that |
I have a lot of books, half of __________ novels.
| A．which | B．that | C．whom | D．them |