He started to work dilligently _____ he came up with the idea of hybrid rice for the first time in the 1960’s.
A.at once | B.the moment | C.for the moment | D.in no time |
Listen! Do you hear someone for help?
A.calling | B.call | C.to call | D.called |
It rained heavily in the south,_______ serious flooding in several provinces.
A.caused | B.having caused | C.causing | D.to cause |
Mrs. White showed her students some old maps ______ from the library.
A.to borrow | B.to be borrowed | C.borrowed | D.borrowing |
Mark ______ have hurried. After driving at top speed, he arrived half an hour early.
A.needn’t | B.wouldn’t | C.mustn’t | D.couldn’t |
People have always been ______ about exactly how life on earth began.
A.curious | B.excited | C.anxious | D.careful |