Van Deemter方程中,影响A项的主要因素是
A. 固定相颗粒大小
B. 载气流速
C. 载气相对分子质量
D. 柱填充的均匀程度
E. 柱温
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"unpredictability"可以被划分成几个词根词缀?
A. 2
B. 3
C. 4
D. 5
This students ID _____ me to travel half price on train.
A. able
B. unable
C. enable
D. enables
Which of the following words has the similar meaning with "schedule"?
A. action
B. agenda
C. agent
D. agency
There is an ____ shortage of water.
A. acid
B. acumen
C. acute
D. acrid