第1题: [单项选择]We know that this is true, but ______ we recognize this truth only in our backward glance. A. all too often B. too often C. all too late D. too late 参考答案:A 答案解析:all too often时常,太多的时候,固定词组,表示失望、遗憾或不耐烦的情绪。
第23题: [单项选择]In 1914, an apparently insignificant event in a remote part of Eastern Europe ______ Europe into a great war. A. inserted B. imposed C. pitched D. plunged 参考答案:D 答案解析:[解析] A项inserted意为“插入,登载”;B项imposed意为“征(税等),强加”; C项pitched意为“投,扔”;D项plunged意为“使陷入”。
第35题: [单项选择]三相半波可控整流电路电感性负载无续流管,输出电压平均值的计算公式是()。 A. Ud=1.17U2cosα(0°≤α≤30°) B. Ud=1.17U2cosα(0°≤α≤60°) C. Ud=1.17U2cosα(0°≤α≤90°) D. Ud=1.17U2cosα(0°≤α≤120°) 参考答案:C