Pieces of bamboo or wood ________ books between 2nd and 5th century AD.A. used to formed B. used to formC. were used to form D. used to beforming
With a lot of problems __________, the new government is now having a hard time.
Though I’ve tried very hard to improve my English, by no means ___________with my progress.
Science and technology have in important ways __________ the improvement of agricultural production.
Mr. Han, my neighbor, is always helping those who are in trouble without expecting anything __________.
He is very sick. I insist that a doctor __________ immediately.