()是口头交际语言。
A.含义明确的语言
B.生动的语言
C.介绍性语言
参考答案:C
(2013 ·湖北武汉武昌高三联考)Smiling doesn't ________ mean you're happy.Sometimes, it just means that you're strong enough to face problems.
A.fortunately
B.eventually
C.deliberately
D.necessarily
什么是安全限值?