第7题: [单项选择]We were surprised because it was the first time they us ______ to lunch. A. invite B. invited C. have invited D. had invited 参考答案:D 答案解析:it is the first time后面的从句用现在完成时，it was the first time后面的从句要用过去完成时，因此D正确。
第18题: [多项选择]由小学到中学，所修习的无非是一些普通的基本知识。就是大学四年，所授课业也还是相当粗浅的学识。世人常称大学为“最高学府”，这名称易滋误解，好像过此以上即无学问可言。大学的研究所才是初步研究学问的所在，在这里做学问也只能算是初涉藩篱，注重的是研究学问的方法与实习。学无止境，一生的时间都嫌太短，所以古人皓首穷经，头发白了还是在继续研究，不过在这样的研究中确是有浓厚的趣味。 参考答案:Primary and secondary school will impart to you only some rudiments of knowledge①．Even what you learn during the four years of university will be something quite superficial too. A university has often been misleadingly②referred to as“the highest seat of learning”③which sounds as if there were no more learning to speak of beyond it. The research institute of a university, however, is the place for preliminary scholarship. But even there④you get only the first taste of learning⑤and the emphasis is on research methodology and practice. Art is long, life is short. That is why some of our ancients continued to study even when they were hoary-headed⑥. They were, of course, motivated by an enormous interest in their studies⑦. 答案解析:[解析] ①汉译英中非常重要的一点就是如何选择主语。本句以primary and secondary school为主语，目的是为了连接下文所讨论的a university和
