Try to spend your time just on the things you find _________.
| A．worth doing them | B．worth being done |
| C．them worth doing | D．worth doing |
— Do you know where David is ? I couldn’t find him anywhere.
— Well. He ______ have gone far –his coat’s still here.
| A．shouldn’t | B．mustn’t | C．can’t | D．wouldn’t |
This cake is very sweet. You _____ a lot of sugar in it.
| A．should put | B．could have put | C．might put | D．must have put |
He paid for a seat, when he ______ have entered free.
| A．could | B．would | C．must | D．need |
— The woman biologist stayed in Africa studying wild animals for 13 years before she returned.
— Oh, dear ! She ______ a lot of difficulties !
| A．may go through | B．might go through |
| C．ought to have gone through | D．must have gone through |
Helen ______ go on the trip with us, but she isn’t quite sure yet.
| A．shall | B．must | C．may | D．can |