活化蛋白C能灭活的因子是（）
A.凝血因子Ⅴa和Ⅷa
B.凝血因子Ⅶa和Ⅹa
C.凝血因子Ⅸa和Ⅺa
D.凝血因子Ⅴ和Ⅷ
E.HCⅡ
参考答案：A
Everyone except Tom and John _______ there when the meeting began.
[ ]
A. is
B. was
C. are
D. were
车用燃气气瓶出现哪些情况下，应按照规定进行检验？
