形成凝血活酶的是()
A.PF3
B.FV
C.CA2+
D.FⅩA
E.FⅧ
参考答案:A, B, C, D
--Have you returned the book to the library _______? --Yes, I have ____ returned it.
A.yet, yet
B.already, already
C.already, yet
D.yet, already
斯科特系统氮气置换时,采用的方法为()。
A、用循环风机置换系统氧
B、用氮气向火炬赶氧
C、用氮气赶氧至焚烧炉
D、将氮气就地放空置换