狗的尾巴还能表达感情呢。它一见主人，尾巴就会yao个不停。

A. they should lead to
B. leading to
C. lead to
D. should they lead to

A. should have been
B. should be
C. must be
D. needed to be

A. 哺乳前后用2％碳酸氢钠溶液清洁口腔
B. 鼓励多饮水，进食前后用2％碳酸氢钠溶液漱口
C. 局部使用锡类散.冰硼散涂抹患处
D. 选用有效抗生素控制细菌感染
E. 随时使用2％利多卡因涂局部止痛

A. has been
B. is
C. are
D. being