is是be动词. be动词包括:am ,is ,are. 如果把一个句子变成疑问句,首先要看这个句子的动词是什么. 如果句中有be动词,直接把be动词提前. 例如: This is a pen.有be动词,直接提前,就是Is this a pen? They are eating apples.Are they eating apples? 如果句中没有be动词,而是实意动词,就得借助于助动词do 或 does 提问. 例如: They had an oral english class yesterday. had 是实意动词.借助助动词提问:Did they have an oral english class yesterday? had 是过去式,所以用did 提问.变为疑问句的时候动词had 要还原为have. He goes to school by bus everyday.go 是实意动词,就得借助助动词does提问.变为:Does he go to school by bus everyday? he 是第三人称单数,所以用does 提问,疑问句中goes还原为go