急性化脓性骨髓炎的X线摄片表现在发病多少时间可出现（）
A.3周
B.2周后
C.1～2周
D.即刻
E.无固定时间
参考答案：B
One can't learn a foreign language well _______ he studies hard.
[ ]
A. though
B. but
C. if
D. unless
“I am astonished, my dear,” said Mrs. Bennet, “that you _____ be so ready to think your own children silly.”
A．might
B．could
C．would
D．should
