第6题: [单项选择]—Do you often visit your grandparents —Mmm...______, I'm afraid. I usually phone them. A. over again B. time and again C. once again D. now and again 参考答案:D 答案解析:[解析] time and again反复,over again和once again均为“又一次”之意。now and again时而,只有D与题意相符。