You can keep all the files and documents          you think it is convenient to get them．

There is never enough time to do everything, ______ there is always enough time to do the most important thing. 

——How do you think I should receive the reporter? ——____ you feel about him, try to be polite.

Try ___ she might, Sue couldn’t get the door open.

 ________ lack of interest, Tom kept trying hard to catch up with others.