下面描述有关PowerPoint演示文稿播放的控制方法，其中( )是错误的。
A. 可以用键盘控制播放
B. 可以用鼠标控制播放
C. 右击鼠标，幻灯片可切换到“下一张”而不能切换到“上一张”
D. 按“↓”键切换到“下一张”，按“↑”键切换到“上一张”
According to the author, the department stores of the 19th century ______.
A. played a role in the spread of popular culture
B. became intimate shops for common consumers
C. satisfied the needs of a knowledgeable elite
D. owed its emergence to the culture of consumption
We can infer from Dr Myers and Dr. Worm's paper that ______.
A. the stock of large predators in some old fisheries has reduced by 90%
B. there are only half as many fisheries as there were 15 years ago
C. the catch sizes in new fisheries are only 20% of the original amount
D. the number of larger predators dropped faster in new fisheries than in the old
社会工作对象的扩大主要表现为( )。
A. 社会工作服务于全体社会成员
B. 从帮助物质生活上最困难的人逐步扩展到所有基本生活遇到困难的人
C. 弱势群体的人数扩大了
D. 社会工作所服务的人数增加了
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