以下对于熊胆主要功效描述正确的是：（）
A.泻火除烦、清热利尿
B.清热解毒，明目，止痉
C.清热解毒，凉血利咽
D.清热、生津、凉血
参考答案：B
灭菌物品有效期一般为多少天？
---What ______ the forest of Yangzhou in the last 30 years?
---Yangzhou has become much greener.
A．has happened to
B．was happened to
C．has happened at
D．is happening
