问题 选择题
下列函数中,最小正周期为π的奇函数为(  )
A.y=sin2xB.y=cos
x
2
C.y=sin(2x+
π
2
)
D.y=cos(
1
2
x+
π
2
)
答案

由于函数y=sin2x为奇函数,且最小正周期为

2
=π,故满足条件.

由于函数y=cos

x
2
为偶函数,故不满足条件.

由于函数y=sin(2x+

π
2
)=cos2x为偶函数,故不满足条件.

由于函数y=cos(

1
2
x+
π
2
)=-sin
x
2
 是奇函数,但最小正周期为 4π,故不满足条件.

故选A.

阅读理解

A good teacher is many things to many people. In my own experience, the people I respect the most and think about the most are the teachers who demanded (要求) the most discipline (纪律) from their students.

I miss one teacher in particular that I had in high school. I think she was a good teacher because she was a very strict person. I remember very vividly (清晰地) a sign over her classroom door. It was a simple sign that said, “Laboratory—in this room the first five letters of the word was emphasized (强调), not the last seven.” In other words, I guess, labor for her was more important than oratory, which means making speeches.

She prepared her work very carefully and demanded us to do the same. We got lots of homework from her. Once she had broken her arm, and everybody in the class thought that maybe the homework load would be reduced, but it continued just the same. She checked our work by stamping her name at the bottom of the papers to show that she had read them.

I think sometimes teachers who demand the most are liked the least. But as time goes by, this discipline really seems to benefit (有益于) the students.

小题1:Which of the following is considered a good teacher by the writer?

A.A patient teacher.

B.An honest teacher.

C.A strict teacher.

D.A hard-working teacher.小题2:The teacher put up the sign over her classroom door ___.

A.to remind the students that this room was a laboratory

B.to advise the students to follow the disciplines

C.to warn the students not to be careless

D.to tell the students to work hard in the classroom小题3:When the teacher’s arm was broken, she ___.

A.gave her students the usual amount of homework

B.gave her students less homework

C.asked her students to check the homework themselves

D.gave her students more homework小题4:What’s the writer’s opinion of discipline?

A.It makes the students dislike their teachers.

B.It does good to the students in the long run.

C.It’s too much for young children.

D.It does more harm than good to the students.

单项选择题