____ they read the book before?参考答案填Have,那么填How long did 为什么不可以呢
问题描述：
____ they read the book before?参考答案填Have,那么填How long did 为什么不可以呢
答
how long 问的是多久了,他们之前读这本书多久了,所以应该写成how long have they read the book before?跟用have意思完全不一样