__ he __ to swim in the river? A. Do...used B. Did...use C. Does...use D. Did...used

此句应该选择b

used to 表示 过去 常常作某件事，而现在不再做了

比如可以对对某个正在吸烟的朋友说 I am surprised to see you smoking,you didn't use to 或者you used not to.

毕竟used to 中used是use的过去式形式。

注意：used to 本身时态不变化，但是它其实就相当于一个过去时的动词短语，在否定句或者疑问句中和其他的动词没有区别。但是可以有两种变化形式，在上面的例句已经都给出了。

used to do sth. didn't use to sth. Did sb. use to do sth.? She used to swim in the pool, didn't she? 也就是说used to 的否定，疑问发生在其所对应的助动词did上。

used to do 表示过去常常做某事，而现在往往不做了 i used to get up early in the morning when i was still a hight school student. be used to doing 表示习惯于做某事（过去习惯于？？）i am used to eating rice now. be used to do表示...被用来做某事 Pig Stem Cells to Be Used to Grow Human Organs?

used to do 过去常常做某事 be used to doing 习惯于做某事 be used to do被用来做某事