肺痨形成的外因为
A．蚊虫叮咬
B．痨虫感染
C．热毒侵袭
D．寒毒直中
E．湿毒侵袭
参考答案：B
—My goodness! The accident might not have happened if we had done it more carefully.
—But we .
A．haven’t
B．wouldn’t
C．hadn’t
D．didn’t
