下列说法错误的是（） A.种群是进化的单位 B.生物进化的实质在_爱下问搜题

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问题单项选择题

下列说法错误的是（）

A.种群是进化的单位

B.生物进化的实质在于种群基因频率的改变

C.生物的变异是定向的

D.突变和基因重组、自然选择及隔离是物种形成过程的三个环节

答案

参考答案：C

完形填空

完形填空。

There are twenty-seven boys and twenty girls in our class. 1 of the boys is English.His 2 is John.He is thirteen.
He likes 3 very much.But he is not good at it.Two of the 4 are American.They are twins.5 names are Mary and
Jane.They are twelve.They ?always? 6 the same cl

othes.They are my 7 . All the other boys and girls are 8 .We
Chinese students all like the English boy and the American girls.They like us,too.We 9 games together and we help
each other.Look,there 10 the twins!They are coming this way.Let's say hello to them.?

( )1.A.One
( )2.A.Class
( )3.A.the football
( )4.A.girls
( )5.A.Their
( )6.A.put
( )7.A.friends
( )8.A.Chinese
( )9.A.do
( )10.A.come

B.Two
B.School
B.football
B.girl
B.They
B.wear
B.sisters
B.English
B.play
B.comes

C.Three
C.name
C.a football
C.boys
C.Them
C.on
C.teachers
C.American
C.have
C.to come

填空题

煤中的硫是以（）、（）和（）三种形式存在于煤中。