在体内，最不稳定的凝血因子是（）。
A.因子Ⅱ
B.因子Ⅻ
C.因子V
D.因子Ⅸ
E.因子X
参考答案：C
It’ll be a great honour if I _________ to the charity evening party next week.
A．invite
B．am invited
C．will invite
D．will be invited
The teacher came in, ______ a smile ______ his face. [ ]
A. with; on
B. on; with
C. with; in
D. and; on
