问题 填空题

“a=0”是函数f(x)=x2+ax(x∈R)为偶函数的______条件(在“充分不必要,充分必要,必要不充分,既不充分也不必要”中选填)

答案

条件:函数f(x)=x2+ax(x∈R)为偶函数,

可得f(-x)=f(x),得(-x)2-ax=x2+ax,

∴-ax=ax,∴a=0;

当a=0时,f(x)=x2+ax,满足f(-x)=f(x),是偶函数;

∴“a=0”是函数f(x)=x2+ax(x∈R)为偶函数的充要条件;

故答案为:充分必要.

阅读理解

B

When a rather dirty, poorly dressed person kneels at your feet and puts out his hands to beg for a few coins, do you hurry on, not knowing what to do, or do you feel sad and hurriedly hand over some money? What should our attitude to beggars be? There can be no question that the world is full of terribly sad stories. It must be terrible to have no idea where our next meal is going to come from. It seems cruel not to give some money to beggars.

Certainly, most of the world’s great religions (宗教) order us to be open-hearted and share what we have with those less fortunate than ourselves. But has the world changed? Maybe what was morally (道德方面) right in the old days, when one knew exactly who in the village had suffered misfortune and needed help, is no longer the best idea. Quite a few people will not give to beggars. Let us look at their arguments.

First, some believe that many city beggars dress up on purpose to look pitiable and actually make a good living from begging. Giving to beggars only encourages this sort of evil (恶行). Secondly, there is the worry that the money you give will be spent on beer, wine or drugs. Thirdly, there is the opinion that there is no real excuse for begging. One might be poor, but that is no reason for losing one’s sense of pride and self-dependence.

Related to this is the opinion that the problem should be dealt with by the government rather than ordinary people. Some people think beggars should go to the local government department and receive help.

It is hard to come to any final conclusion; there are various cases and we must deal with them differently. A few coins can save a life in some situations, and even if the money is wasted, that does not take away the moral goodness of the giver.

59. What is mainly discussed in the passage?

A. Moral deeds of people.         B. Religious activities of the church.

C. Moral goodness of the giver.     D. Arguments on giving to beggars.

60. What can we infer from the sentence “But has the world changed?” in the second paragraph?

A. People no longer know who suffers misfortune in the village.

B. Some people will not do what was morally right in the past .

C. We don’t meet with those who need help any more.

D. Now it is the government’s duty to help the beggars.

61. Which of the following is NOT mentioned in the passage?

A. Some people dress up to pretend to be beggars.

B. Some beggars want money to help their children go to school.

C. Some beggars use the money to buy drugs.

D. Some beggars have no excuse for begging.

62. In the last paragraph, the writer thinks that it is hard to come to any final conclusion, because______.

A. the cases can be so different

B. there are so many beggars

C. there is so much money wasted

D. there are so many different arguments

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