单项选择题
A. if;when B. if; as long as C. whether; as long as D. whether; since
It took them more than ten years to ______ the defensiv...
单项选择题It took them more than ten years to ______ the defensive works.()
A. build B. build into C. build on D. build up
The daily news reported that 305 people ______ with SAR...
单项选择题The daily news reported that 305 people ______ with SARS in Guangdong Province.()
A. has ecome infected B. has become infecting C. had become infected D. had become infecting
Mary saw her son ______ the piano when she came to the ...
单项选择题Mary saw her son ______ the piano when she came to the room.()
A. playing B. play C. played D. to play
