[单项选择]The crankcase of many diesel engines are kept under a slight vacuum by the (). A. scavenging action of the piston B. piston type vacuum pump taking suction off a differential manometer C. gland exhausting manometer D. crankcase exhaust fan
第20题: [单项选择]A series of strikes have ______ many of the basic industries in that country. A. crippled B. damaged C. changed D. decreased 参考答案:A 答案解析:[试题分析] 词义辨析题。辨析意义相近的词。
[详细解答] crippled v. 严重削弱,使残废;damaged v. 损坏; changed v. 改变;decreased v. 减少
第24题: [单项选择]A tow astern is veering from side to side on its towline. The best way of controlling the action is to(). A. trim the tow by the bow B. trim the tow by the stern C. list the tow to windward D. adjust the length of the towing bridle 参考答案:B