题目

They used to nod to each other when they met, and now and then they _______ a word or two.A.would exchange  B.were used to exchanging  C.used to exchange   答案： A 本题考查 would + 动词原形表达过去常常发生的习惯，它和 used to + 动词原形的区别就是它能和时间状语连用，本句的时间状语是now and then 。  

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