People are advised not to drive after drinking, but __ seems not to help a lot.

____ do you think is the cleverest student in our grade.

If a book is in French, ____ will be a challenge for me．

—You look great! Were you on vacation or ________？—You got it. I've just come back from America.

---What do you think of these two books?---_________ of them are interesting. And I’ve read them several times.