A.条件（1）充分，但条件（2）不充分. B.条件（2）充分，但条件

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问题填空题

A.条件（1）充分，但条件（2）不充分.

B.条件（2）充分，但条件（1）不充分.

C.条件（1）和（2）单独都不充分，但条件（1）和条件（2）联合起来充分.

D.条件（1）充分，条件（2）也充分.

E.条件（1）和（2）单独都不充分，条件（1）和条件（2）联合起来也不充分.

x，y∈R，则|x|+|y|=|x-y|．
(1)x＞0，y＜0； (2)-x＜0，y＞0．

答案

参考答案：D

解析：

[提示] |x-y|=|x+(-y)|=|x|+|-y|，从而x(-y)≥0，xy≤0．从而条件(1)、条件(2)单独都充分．故选(D)．

改错题

短文改错。

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中

共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏字符号（^），并在其下面写出该加的词。

删除：把多余的词用斜线 (＼)划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：(1) 每处错误及其修改均仅限一词；

(2) 只允许修改10处，多者（从第11处起）不计分。

A boy who was cleaning the shoes in the street said to a young man passed by, "Let me clean

your boots. It just spends you only a penny." But the man refused. Then the boy told him that he

will clean his boots for nothing. The man agreed, and soon one of the boot shone brightly. Then

he put the other boot on the box, and the boy refused to clean it if he was paid two pence for his

work. The young man refused pay something and went away. But the well-cleaning boot made

the dirty one so badly that he could not walk on. He turned back and gave the boy two pence.

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判断题

排水剪切试验过程中孔隙水压力始终为零。