【单选题】采用气相色谱法分析羟基化合物,对 C4~C14 的 38 种醇进行分离,较理想的分离条 件是 ( )
A.
填充柱长 1m, 柱温 100C 、载气流速 20mL/min
B.
填充柱长 2m 、柱温 100C 、载气流速 60mL/minC
C.
毛细管柱长 40m 、柱温 100C 、恒温
D.
毛细管柱长 40m 、柱温 100%C ,程序升温
【单选题】—I’m going to HongKong for vacation. —____________.
B.
I’m sorry to hear that
【简答题】被子植物次生木质部的细胞组成有 、 、 和 。
【单选题】According to the passage, which of the following statements about 'stress' is most probably right?
A.
Stress isn't a critical factor which affects the result of dieting.
B.
To deal with stress, one has to know the changes of his/her behavior.
C.
When facing stress, people tends to have no appetite.
D.
One shouldn't eat anything at all during work when stressed.
【简答题】• Oh dear I’m sorry to hear that.
【判断题】“乌金衣”是指熊胆表面有一层黑色光亮的薄膜。
【单选题】–You know my daughter failed in the application to the Columbus University. – I’m sorry to hear that. But she never pays attention to her oral English. –____________________.
【单选题】采用气相色谱法分析羟基化合物,对C4~C14 38种醇进行分离,较理想的分离条件是()
A.
填充柱长1m、柱温100℃,载气流速20ml/min
B.
填充柱长2m、柱温100℃,载气流速60ml/min