第4题: [单项选择]______ you go on the earth, there is always gravity to keep your room from falling off. A. When B. Whenever C. Since D. Because 参考答案:B 答案解析:A、B、C、D四个选项都为关联词,句法上都可置入空当处,但C和D置入后,句子意思不通。A和B可以置入,但意思略有区别:whenever具有强调意义,它相当于no matter when。根据主句中al