—Would you like some______?—Thank you, but l don’t like it.

—Where did you get this book?—I picked it up from a second-hand bookshop if you ______ know.

The room is in a terrible mess; it        have been cleaned.

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

 — Are you going to Beijing by air?— It’s fast, but expensive. So I’m not sure. I _____ take a train.