18.--- Tom has a lot of parties recently.---Yes, that may ____ why he didn’t do well in the test.A, sum up B. add up to C. account for D. make sense of
Qiandao Lake, widely known ______ a tourist site, is famous _____ its clear and drinkable water.
We have every reason to believe that __________ 2012 London Olympics will be ________ great success.
—Madam, could you please tell me how to get to the nearest post office? —_______
Entering the room, I found Mary ______at the desk and ______a letter.
_________on the main street, the market was busy yesterday.