问题 选择题
下列说法正确的是(  )
A.一元二次方程的一般形式是ax2+bx+c=0
B.一元二次方程ax2+bx+c=0的根是x=
-b±
b2-4ac
2a
C.方程x2=x的解是x=1
D.方程x(x+3)(x-2)=0的根有三个
答案

A、一元二次方程的一般形式是ax2+bx+c=0,但要强调a≠0,所以,A错误;

B、忽视了一元二次方程的有解的条件,即a≠0且b2-4ac≥0,所以,B错误;

C、方程x2=x可化简为x2-x=0,解得:x=0或1,所以,C错误;

D、方程x(x+3)(x-2)=0,即x=0或x=-3或x=2,所以,D正确;

故本题选D.

阅读理解

This year some twenty-three hundred teen-agers (young people aged from 13-19) from all over the world will spend about ten months in U.S. homes . They will attend U. S. schools , meet U.S. teenagers , and form impressions of the real America . At the same time , about thirteen hundred American teenagers will go to other countries to learn new languages and gain a new understanding of the rest of the world .

Here is a two-way student exchange in action . Fred , nineteen ,spent last year in Gemany with George’s family . In turn , George’s son Mike spent a year in Fred’s home in America .

Fred , a lively young man , knew little German when he arrived , but after two months’ study , the language began to come to him . School was completely different from what he had expected-much harder . Students rose respectfully when the teacher entered the room . They took fourteen subjects instead of the six that are usual in the United States . There were almost no outside activities .

Family life , too , was different . The father’s word was law , and all activities were around the family rather than the individual. Fred found the food too simple at first . Also , he missed having a car .

“Back home ,you pick up some friends in a car and go out and have a good time . In Germany , you walk , but you soon learn to like it .”

At the same time , in America , Mike , a friendly German boy , was also forming his idea . “I suppose I should criticize American schools .” He says , “it is far too easy by our level . But I have to say that I like it very much . In Germany we do nothing but study . Here we take part in many outside activities . I think that maybe your schools are better in training for citizens . There ought to be some middle ground between the two .”

小题1:The whole exchange programme is mainly to         .

A.help teenagers in other countries know the real America

B.send students in America to travel in Germany

C.let students learn something about other countries

D.have teenagers learn new languages小题2:Fred and Mike agreed that         .

A.American food tasted better than German food

B.German schools were harder than American schools

C.Americans and Germans were both friendly

D.there were more cars on the streets in America小题3:What is particular in American school is that         .

A.there is some middle ground between the two teaching buildings

B.students usually take fourteen subjects in all

C.there are a lot of after-school activities

D.students go outside to enjoy themselves in a car小题4:After experiencing the American school life , Mike thought         .

A.the easy life in the American schools was more helpful to the students .

B.German schools trained students to be better citizens .

C.American schools were not as good as German schools

D.a better education should include something good from both America and Germany

判断题