There’s no doubt2013 will bring more change when the world economy is still unclear.

China is larger than ________ country in Africa(非洲).

David， is that man your Chinese teacher— It ___________ be him. He’s having a meeting.

It took ______ building supplies to construct these energy-saving houses. It took brains, too.

s warn that medical waste from hospitals, if properly, may lead to spreading diseases.