______ over and over again, but he still couldn’t understand.
| A．Having explained | B．Having been explained |
| C．Explaining | D．It had been explained |
Between the two generations, it is often their different views of life and value _____ cause family conflicts.
| A．which | B．what | C．who | D．that |
. With their son ______ a foreign college now, the parents have some financial problems now and then.
| A．to attend | B．attending | C．attended | D．having attended |
Another primary school is reported _______ for children in Wen Chuan now.
| A．to have been built | B．to have built |
| C．being built | D．to be building |
The citizens of Beijing are proud of _______ they have done to make Beijing a beautiful city.
| A．that | B．which | C．what | D．how |
. I am very grateful to my high school teachers, without ______ help I wouldn’t be so excellent.
| A．whom | B．them | C．which | D．whose |