----What do you think of the Chinese language today? ---- Quite popular. It __________ an important role in communicating with other countries. More and more foreign friends are learning Chinese.
________ caused the accident is still a complete mystery.
I’m afraid he’s more of a talker than a doer,which is ________ he never finishes anything. (2011·山东,26)
Scientists study ________ human brains work to make computers. (2012·四川,17)
It suddenly occurred to him________he had left his keys in the office. (2012·江西,25)
Jerry did not regret giving the comment but felt ________ he could have expressed it differently. (2012·北京,24)