句型转换。
1. Li Ming has already finished his homework.（改为一般疑问句）
_____________ Li Ming _____________ finished his homework yet?
2. Both of the boys are good at basketball.（改为否定句）
______________ of the boys _____________ good at basketball.
3. Laura has never been to Hong Kong.（改为反意疑问句）
Laura has never been to Hong Kong, ____________ ___________?
4. Mr. Brown has taught in the school since 1990.（对划线部分提问）
_____________ _____________ has Mr. Brown taught in the school?
5. The twins came to China three years ago.（改为现在完成时态的句子）
The twins have _____________ _____________ China for three years.
