大黄泻下作用的主要成分是A．脂肪油 B．硫酸钠 C．结合型葸苷 D．游离型葸苷 E．

Passage One

Which of the following is NOT considered bad table manner

A．Smack one’s mouth to show that he enjoys the meal.

B．Make a loud sound when one is drinking soup.

C．Speak only when one has swallowed the food in his mouth.

D．Excuse oneself from dinner table by saying he is going to the toilet.

电子钱包是电子商务购物活动中的（）。

A、电子货币 

B、信用卡 

C、一种支付工具 

D、网络应用程序 

23×25×4=23×（25×4），这是应用了______律．

信息在感觉通道内迅速被登记并保留的记忆是短时记忆。

液压系统的定期保养主要是粗滤器、精滤器和（）的保养。

A.冷却器

B.管路

C.操纵阀

D.接头