题目

The government required that every effort ____to bring down house prices.A.should make B.would be made C.be made D.must be made 答案：【答案】C【解析】考查虚拟语气。句意：政府紧急督促要尽一切努力降低房价。此处require后宾语从句用should+动词原形形式，should被省略；宾语从句还是make every effort to do sth被动形式。故选C。把R1与R2串联在电压为4.5伏电源上，R1两端的电压是1.5伏通过R2的电流是0.1安培，则R1是________欧姆，R2是________欧姆，如果把它们并联在同一电源上，电路中总电流是________安培．