煎膏剂制备时加入炼蜜或炼糖的量一般不超过清膏量的（）
A.1倍
B.2倍
C.3倍
D.4倍
E.5倍
参考答案：C
It never _____ humans until the mid1990s that some animals can be cloned.
A．occur
B．is occurred
C．occurred to
D．occurred
排尿反射初级中枢位于（）
A.胸部脊髓
B.腰部脊髓
C.骶部脊髓
D.盆神经
