May is a new student, ______? [ ]
A. don't she
B. doesn't she
C. is she
D. isn't she
答案:D
慢性支气管炎的临床分型有()
A.支气管炎型
B.气肿型
C.混合型
D.喘息型
E.单纯型
除沫器的主要功能有哪些?