It is sometimes difficult for a newly established corporation to ______ the changing demands of the market.

(2014·四川省攀枝花市模拟)—Tom has played a lot of computer games recently.—Yes，that might ________his failure in the mid­term examinations.

It was not until dark _____ he found _____ he thoughtwas the correct way to solve the problem

Never before______ so highly successful inhis attempts to forecast the weather accurately on a small scale．

You look sad ____?— Oh, my grandmother’s very ill