_____ you _____ your homework yet?—Yes, I _____ it ten minutes ago.

the students in this school is about four thousand,of them are boys．

In order to enter the PE exam, now we spend at _____ least half _____hour a day at school.

―It’s a pity that many people lost their lives in the wreck accident in South Korea.― I think so. It’s not wise _______ the captain to _____ first.

一Are you going to Guilin by plane?一It’s fast but expensive, so I’m not sure．I ________ take a train．