问题 单项选择题

,则f′x(x,1)=()。

A.0

B.1

C.2+x

D.x2+y2

答案

参考答案:B

解析:

,f′x(x,1)=1,选B。

求完偏导数后将某点代入即可求得偏导数在该点的值。

完形填空

Breakfast is very important. It is one of the most important(最重要的)  36 of the day. To keep healthy, everyone should  37  a good breakfast. 38  the right food is necessary for good health. We may have eggs, bread, milk  39 breakfast.

Many students go to school without breakfast  40 they get up late or their parents don’t cook for them. It’s  41 for their health.

  42 breakfast children may not grow fast and may not study and play very well at school. They may  43  . And when they’re ill, they will  44 a long time in recovering (恢复).

I think everyone should have some good   45  habits. It is necessary.

小题1:A. meal                B. meals             C. dinner

小题2:A.to have              B. have              C. has

小题3:A.Eating               B. Eats              C. Eat

小题4:A.in                   B. on               C. for

小题5:A.because              B. so                C. but

小题6:A.good                B .bad               C. better

小题7:A.Without              B. With             C. Not have

小题8:A.ill                   B .are ill             C .be ill

小题9:A.spend                B. take              C .make

小题10:A.health               B .healthy             C. bad

单项选择题