Have you written anything on Chinese traditional medicine so far?— _________, but I have a plan for it.

It _____________ me twenty minutes to come to school by bike.

How many students are there in your school?—_______ students, I think.

I always make mistakes in my math exams. What should I do? –I think you should be _________.

She is the only one of the girls in our class______ been to the United States.