单晶体的主要特征是：（1）在外形上具有______（2）在导热、导电_爱下问搜题

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问题填空题

单晶体的主要特征是：（1）在外形上具有______（2）在导热、导电、机械强度等物理性质上具有______；（3）熔化时有______，而多晶体只具有上述的第______条特征．

答案

单晶体的主要特征是：（1）在外形上具有规则的几何形状（2）在导热、导电、机械强度等物理性质上具有各向异性；（3）熔化时有一定的熔点，而多晶体只具有上述的第（3）条特征．

故答案为：规则的几何形状，各向异性，一定的熔点，（3）．

完形填空

Directions: For each blank in the following passage there are four words or phrases marked A, B,C and D. Fill in each blank with the word or phrase that best fits the context.
I hadn’t even got a chance to enter the store before an African American woman approached me and asked if I would help her return an item. The item she has _____ was intended for her daughter, but she had already received a similar one. The lady _____ to exchange the item for something else in the store but she was told she needed an ID or the deal could not take place.
I went to the ____ with the woman so we could use my ID. The sales associate immediately started ______ her of asking the first random person she saw to help her. Although that was ___ , I didn’t understand why it mattered. After all, not everyone is given the opportunity to ____ an ID in this country.
Then, we asked to speak with a manager, who explained that there was no way to return the item without a receipt and then went on to say the woman could not ______ she purchased the item.
“If I , a young white female, were to enter the store and request you to make an exchange without a receipt, I would not be _____ the privilege--- as I have proof from the past.” I said. He must have realized at that moment what he had done, because he _____ to exchange the item.
There are many valuable lessons in the story. The first is to help a stranger in need. I hesitated when the woman asked for my help, but ______ in my hand I asked myself, “ Why not? What valid reasons do I usually have?” I had none, so I helped her.
The second lesson is not to judge a book by its ______. The woman looked poor, but she _____ the same treatment as anyone else does.

D．appreciated

单项选择题

经济手段的最基本的特点是（）。

A．利益性

B．强制性

C．规范性

D．稳定性