简述稀土元素主要的分离方法？离子交换法和萃取法的基本原理。

A、Only one mistake or ambiguity is present in the subject matter of the entire contract

B、Out of several contracts drafted simultaneously between two parties, one has a mistake in its subject matter that does not concern the other contracts

C、Only one party is mistaken about a material fact regarding the subject matter of a contract

D、A single mistake about a material fact in the subject matter of a contract appears several times in the contract

A、We should write a clear subject line in a business email.

B、A subject line of an email is the first indication of how important that email is.

C、“Contracts for tomorrow’s investor meeting” is better than “Information for meeting”.

D、All of the three.

Perhaps we should climb out of the window and jump down？ It's only two floors.

()We'd better wait for the rescue.

A. That's a good idea.

B. No, we can't do that.

C. I think we will kill ourselves.

We’ll sign two originals, each () Chinese and English language.

A．in

B．on

C．with

D．/

A．Most of us should take more exercise.

B．It's better to live in the town.

C．The brain contracts if it is not used.

D．The more one uses his brain, the sooner he becomes old.

A、A. It is communication between people of different cultures.

B、B. We need understanding and acceptance in intercultural communication.

C、C. During the process of intercultural communication, one should turn one’s back on one’s own culture.

D、D. We should develop tolerance and acceptance in intercultural communication.

Constant smiling without apparent reason ______.

A．is a sign of one's friendliness

B．is a sign of one's unfriendliness

C．makes people feel happy

D．makes people feel uncomfortable

A、We should cover as many points as possible in an argument.

B、We'd better build our argument in only one important aspect.

C、We can't construct the argument in two opposite dimensions.

D、The points in an argument should not overlap with each other.

What should we avoid doing if we want success according to the man in the conversation？

A．Enduring what may come in life.

B．Having a disproportional belief in one’s abilities.

C．Having little confidence in one’s abilities.

D．Willing to listen to other people.