Weknowthatasmileisusuallyasignthatpeoplefeelfriendlyan...

问题详情：

 We know that a smile is usually a sign that people feel friendly and happy, but _____ we don’t know who the new person is?

  A. what if                      B. how come            C. what about                 D. why not

【回答】

A

知识点：固定句型

题型：选择题