单项选择。
Here some pencils for every teacher now. [ ]
A. was
B. were
C. is
D. are
答案:D
舱位
HLA-B27与强直性脊柱炎呈正相关的亚型有()
A.B2705
B.B2702
C.B2709
D.B2706
E.B2704