留下历史的瞬间,探寻历史的足迹。下图乔冠华开怀大笑是因为
A.万隆会议的成功召开
B.中国恢复在联合国合法席位
C.中美正式建立外交关系
D.亚太经合组织会议在上海举行
答案:B
Mrs. Smith speaks very loudly _____ all the people can hear her clearly. [ ]
A. When
B. so that
C. because
D. why
什么是系统分析和系统评价?