点（2，-2）是函数f（x，y）=x（4―x）―y（y+4）的（）。 A.极小值点_爱下问搜题

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问题单项选择题

点（2，-2）是函数f（x，y）=x（4―x）―y（y+4）的（）。

A.极小值点

B.非极值点

C.非极值驻点

D.极大值点

答案

参考答案：D

完形填空

完形填空。
     Near our school there is a store. It's    1     but there're _ 2     of school things. Do     3     like
exercise books, erasers, pens     4     color pencils? They are.     5    . Big erasers are just one yuan
6     and small ones are only 0.5 yuan. The color pencils are just    7    2 yuan.l want the cartoon
pencil sharpener. It is      8     expensive, either. I will take     9    .Do you want some school things for
yourself? Just come    10   this store.

( )1. A. big
( )2. A.lots
( )3. A.I
( )4. A. so
( )5. A. expensive
( )6. A. one
( )7. A. for
( )8. A. not
( )9. A. them
( )10. A. for

B. small
B. lot
B. they
B. and
B. cheap
B. every
B. on
B. no
B. it
B. up

C. long
C. many
C. you
C. but
C. dear
C. each
C. in
C. /
C. that
C. to

单项选择题

公共物品的非竞争性是指（）。

A.消费者数量不多

B.生产成本为零

C.消费者对某一种公共物品的消费并不影响其他人对该公共物品的消费

D.公共物品可以由任何消费者进行消费，其中任何一个消费者都不会被排除在外