_____ you _____ to go to the park when they were children?

_____ you _____ to go to the park when they were children?
[ ]
A.Did,useB.Did,usedC.Do,used D.Do,use

A.Did,use,放心采用.
再问： 为什么不是B
再答： I used to do sth 我过去常(做)....used是过去时啊，转为问句，自然是Did you use to...，换个词，I went to the shop，换为问句，你就不能说Did you went to the shop？而是did you go to the shop？ 另外，很多人（包括英美人士）在不正式的情况下也会说Did you used to... 但这是种很不规范的表达，考试，写作中尽量避免。 希望对你有所帮助。