指出下列哪些参数改变会引起相对保留值的增加()。
A.柱长增加
B.相比率增加
C.降低柱温
D.流动相速度降低
参考答案:C
He had his camera ready ________ he saw something that would make a good picture.
A.even if
B.soon after
C.in case
D.so that
中华人民共和国第一任国家 * * 和政务院(国务院) * * 分别是谁?