题目

—Betty, where does the great noise come from?—A group of boys_________(play) football at the back of our house. (所给词的适当形式填空） 答案：【答案】are playing【解析】考查动词时态和主谓一致。句意：——贝蒂，这么大的噪音是从哪里来的？——一群男孩正在我们房子后面踢足球。结合上文“Betty, where does the great noise come from?”可知噪音是正在发出，男孩子们正在踢球，应用现在进行时，且主语为A group of boys，谓语动词用复数。故填are playi如图，是的直径，弦，，，则阴影部分的面积为（ ）A. 2π B. π C. D.