重度缺氧时SaO可降到小于（）
A.80%
B.75%
C.70%
D.65%
E.60%
参考答案：E
The average cost of school residential trips was ￡ 48 in primary schools and ￡ 55 in secondaries in 2003, but ￡ 144 and ￡ 274 in 2009．
A．regularly
B．relatively
C．respectively
D．responsibly
下列组合不正确的是
A．ACTH-肽类激素B．TSH-蛋白质类激素C．Insulin-类固醇激素D．Cortisol-类固醇激素E．NA-邻苯二酚胺
