21.［2012三明模拟］—Jimmy had a lot of parties recently.
—Yes, that might ________ why he didn’t do well on the test.
A. come up with B. bring about
C. account for D. make sense of
22. The idea they have come up with sounds great, but it remains ________ whether it works well in practice．
A. to see B. to be seen C. seeing D. seen
