酶的化学本质是蛋白质，目前发现的所有的酶都是蛋白质。 ( )
参考答案：错
_______ from her parents, she was left with her two young sisters--aged three and seven.
A．Being separated
B．Having been separated
C．Having separated
D．Had been separated
空气的平均CT值正常波动范围不应超过
A．±1HU
B．±2HU
C．±3HU
D．±4HU
E．±5HU
