问题 单项选择题

下表是生长素类似物2,4-D溶液对某植物插条生根影响的实验处理结果,有关该实验的说法错误的是()。

A.每组选取生长状况基本相同、数量相同的枝条

B.各组处理枝条的时间可以不同

C.丙组加入等量的蒸馏水,起对照作用

D.甲组2,4-D溶液浓度较适宜.具有促进作用

答案

参考答案:B

解析:

B。解析:本实验的自变量是2,4-D溶液浓度,因变量是生根数量,植物插条生长状况、每组的枝条数量都是无关变量,无关变量各组的设置要遵循等量性原则,A正确、B错误。丙组加入等量的蒸馏水,对甲、乙组起对照作用,甲组2,4-D溶液浓度促进生根,乙组抑制生根,C正确。和丙组对照,可以看出甲组2,4-D溶液浓度较适宜,具有促进作用.D正确。

阅读理解

阅读理解.

    Many places in the world need more fresh(淡的)water. Every country is trying to find ways to turn

salt water into fresh.

   Why aren't there many factories like the Symi factory?

   In some places,the sun isn't hot enough,or it doesn't shine every day. In these places ,other ways of

heating (加热)sea water can be used. These ways cost more money ,but they work faster than the sun.

By boiling (煮沸)sea water with high heat ,a lot of fresh water can be made quickly.

   But heating is not the only way to get fresh water from salt water. Other ways are tried. One way is

freezing (冷冻). The fresh part of salt water freezes first. To get fresh water, the pieces of ice are taken

out. Which way is best? The one that gives the most water for the least money. It may be a different

way for each place. Symi's way seems very good for small, hot places. It doesn't make very much

water at a time. But the factory is easy to build and cost little.

   That's why people in many dry places talk about Symi!

1 .From the passage we know that fresh water ________.

A .is needed in many countries      

B .is needed in every country

C .is very important for factories    

D .is very important for factories

2 .The Symi factory ________.

A .is a fresh-water factory

B .can be built everywhere

C .can make much fresh water at a time

D .doesn't need sunshine every day

3.Which is the best way for small and hot places to get fresh water?

A.Boiling or heating the sea water.

B.The way in sunny places.

C.The Symi's way.

D.Freezing the sea water in cold places.

4.The writer is mainly talking about ________.

A.water-making factories in different countries

B.the ways of making fresh water from sea water

C.hot places and dry places

D.how to make good use of the sunlight

5.Which is wrong?

A.New ways are tried to get fresh water.

B.Heating can make a lot of fresh water quickly.

C.The best way is to get the most fresh water with the least(最少)money

D.The Symi's way doesn't work in dry places .

填空题