(2013·安徽安庆三模)—She looks very happy.She________have passed the exam.—I guess so.It’s not difficult after all.

Changing the design of a new product may ____ the riskof its production in the market．

Many sailors think that a thick fog is their ________ enemy.

Could you tell me something about that boy-Sorry, I don’t know anything about him. Weare ______.

t at the historic meeting ____many an official on Nov 7, of course President Xi Jinping and Ma Ying-jeou _________.