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问题 单项选择题

下列关于File类的叙述中，正确的是( )。

A．File类是java. io. file包中的非流类

B．File类以系统相关的方式描述文件对象的属性

C．File类不能读写文件

D．File类不能操作文件属性

答案

参考答案：C

解析： File类是java. io包中的非流类，它以系统无关的方式描述文件对象的属性。File类只操作文件在磁盘上的属性，而读写文件内容的功能则需要流类提供。

单项选择题

A group of frogs were traveling through the forests, but unluckily two of them fell into a hole. The other frogs tried to help them. When they saw how (16) the hole was, they cried to the two frogs that they could not be saved. The two frogs didn’t (17) and tried their best to jump up out of the hole. The other frogs (18) saying that they were sure to die. (19) ,one of the two frogs, who heard what the other frogs were saying, (20) ,then he fell down and died.
The other frog, however, (21) to jump as hard as he could, and at last made it out. When he (22) , the other frogs asked, "Didn’t you hear us" The frog, who had a poor (23) , explained, "I thought you were encouraging me all the time. "
The story teaches us a (24) : There is power(力量) of life and death in the tongue. An (25) word to those who are down can help them out while a discouraging word can kill them.

Ⅱ. 完形填空/Cloze

A．happened

B．continued

C．planned

D．wanted
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单项选择题

RNA聚合酶中促进磷酸二酯键生成的亚基是

A．原核RNA聚合酶亚基δ
B．原核RNA聚合酶亚基α
C．原核RNA聚合酶亚基β
D．原核RNA聚合酶亚基β′
E．原核RNA聚合酶亚基σ
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