I don't know the girl _____ Helen. [ ]
A. calling
B. called
C. calls
D. is calling
答案:B
At present,there is little doubt ________ short message plays an increasingly important role in our lives.
A.whether
B.if
C.that
D.which
鉴定真菌最常用的简便方法是()
A.革兰染色后镜检
B.动物接种
C.血清学鉴定
D.皮肤变态反应
E.直接镜检形态结构