采掘过程中可任意扩大和缩小设计规定的煤柱。
参考答案：错
Here are your boots. Put . [ ]
A. on them
B. them on
C. it on
D. on it
cAMP能别构激活下列哪种酶
A．磷脂酶A
B．PKA
C．蛋白激酶C
D．蛋白激酶G
E．酪氨酸蛋白激酶
