W: Did you go to the concert last night
M: Oh, yes. It should have started at 7:15, but it was delayed 15 minutes. I had waited for twenty minutes before it began.
When did the concert begin( ). A. 7:15. B. 7:30. C. 7:50. D. 7:35. 参考答案:B
第31题: [单项选择]对吸尘器操作使用描述正确的是()。 A. 根据使用次数多少,每三年要请专业人员保养检修一次 B. 每次使用完毕,应先将积尘袋中的灰尘清除干净,再断开电源 C. 吸尘器可吸尖硬及大块杂物,如铁钉、玻璃片等 D. 使用前应检查电源线及插头是否完好,储尘袋是否完好无积尘 参考答案:D