5.harvest is reached,farmers grow

4.It is the children who often help the father and mother do the farm work.

3.On this arable land the farmers produce food for the whole population of China.

2.stays the same,matter how

1. It was from the early 1990s that scientists started to develop new techniques to increase production.

1.effects　2.variety　3.delegation　4.techniques　 5.shortage　6.greenhouses　7.damaging　8.against　 9.guide　10.ploughing

1.produce　2.effect　3.leader　4.sugar-cane 　5.tobacco　6.local　7.technique　8.pump　9.irrigation　10.depend on　11.short of　12.root　trol　15.stand for　16.wisdom　17.gardening18.practical　dition　20.sunflower

根据提示写一篇短文。

中国有着悠久的农业史。早期中国科学家的智慧如今仍非常有用。贾思勰就是中国早期农业科学家之一。他花大量的时间研究农业，收集信息，做实验，学习农民的经验。他写了一本书叫《齐民要术》，包括了种蔬菜、果树、养猪、羊、鱼等方面的建议。是一本农业生产的实际向导。

Unit 19　Mordern agriculture

Which is best way to learn a language? We should 　　　　　　　　　 1._________

remember if we all learnt our own language well 　　　　　　　　　　　　　　　　　 2._________

when we are children.If we could learn a second 　　　　　　　　　　　　　　　　　 3._________

language in the same way,it will not seem so 　　　　　　　　　　　　　　　　 4._________

difficult.Think of that a child does.It listens 　　　　　　　　　　　　　　　　　　　　　 5._________

to what people say and it tries to imitate(模仿)　　　　　　　　　　　　　　　　 6._________

what it had heard.When it wants something,it 　　　　　　　　　　　　　　　　 7._________

has to ask it.It is using the language.It is　　　　　　　　　　　　　　　　　　　　 8._________

talking in it and thinking with it all the time.　　　　　　　　　　　　　　　　　　　　　 9._________

Because people have to use a second language all 　　　　　　　　　　　　　 10._________

the time,they would learn it quickly.

B

Besides providing an ideal environment(理想环境)for sea plants and animals to live in,seawater has other values,one of which is that it constantly moves,and its movements produce energy.

The most obvious movements are waves and the tides.Winds causes the waves,and the gravational pull of the moon and the son causes tides.In places like the Bay of Fundy in Canada,the difference between the high and low tide level can be as much as 40 feet.

France and Britain are now trying to use energy in the tides to produce electricity.Waves can produce electricity and some experiments are taking place to learn more about this.One of the most encouraging areas of research uses the difference between the temperature of seawater at the surface and deep down to produce electricity.

6.One of the values of seawater is that _________.

A.it has no plants in it

B.it pulls the sun and the moon

C.it flows all the time

D.it feeds all the time

7.Waves and tides are caused by_________.

A.the same forces

B.different forces

C.their own movements

D.plants and animals

8.According to the passage,which of the following is not true?

A.The temperature difference of seawater can produce electricity.

B.The energy in the tides can produce electricity.

C.Waves can produce electricity.

D.The plants and animals in the ocean can produce electricity.

9.It is being tried in _________ to use energy in the tides to produce electricity.

A.many countries in the world

ada

C.some developed countries

D.the United Nations

10.The best title for the passage is_________

A.Tides and Waves

B.How to Produce Electricity

C.Seawater

D.Another Cheap Energy