Weknowthatasmileisusuallyasign

问题详情：

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

   A. that; what if         B. when; what         C. when; how about   D. if; how

【回答】

A

知识点：连词

题型：选择题