30．Frank’s marriage to the billionaire’s daughter got him through his hardest time, ________ years later he wondered what he could have done differently 。
| A．therefore | B．and | C．however | D．but |
John promised his parents he _______ not smoke again, and he has not smoked ever since.
| A．would | B．could | C．should | D．might |
My brother left home five years ago. I _______ nothing from him up to now.
| A．hear | B．heard | C．have heard | D．had heard |
The power to our region has been _______ by the heavy snow.
| A．cut off | B．cut down | C．cut away | D．cut up |
______more effectively with foreign firms, many Chinese firms have turned to new technology．
| A．Being competed | B．To compete | C．Competing | D．Competed |
Those books ______ in brown paper are for the kids so that the kids will not easily tear them
up．
| A．to do with | B．done up | C．being done | D．having done over |