[单项选择]Great efforts to increase wheat production must be made if bread shortages ______ avoided.
A. will be
B. are to be
C. can be
D. were to be

[单项选择]Why should we increase the production of sugar


A. It tastes sweet.
B. We can save plenty of land.
C. We can get more energy.
D. It is one of the most highly concentrated of energy foo

[单项选择]To produce a mighty book, you must choose a great

[单项选择]No sooner had they got in the wheat than it began to rain heavily.
A. 他们刚收割完小麦就开始下大雨了。
B. 他们还没收割完小麦，就下大雨了。
C. 他们在下大雨前，收割完了小麦。
D. 他们收割小麦前，就开始下大雨了。

[单项选择]Because of the poor harvest, wheat prices have ______ in the last six months.
A. added
B. jumped
C. amounted
D. developed

[单项选择]（）got in the wheat than it began to rain heavily.
A. No sooner had they
B. No sooner have they
C. No sooner they
D. No sooner they had

[单项选择]Most of corn and wheat is ______.


A. sold to feed people
B. exported to foreign countries
C. sold to fatten cattle and pigs
D. sold as food

[单项选择]There are few places in this country ______ wheat can't grow well.


A. where
B. which
C. when
D. if

[单项选择]Before 8,000 B.C. wheat did not grow as prolifically ______ it does today.


A. like
B. as
C. for
D. than

[单项选择]The local communities have failed in their efforts to______ with unemployment.


A. settle
B. cope
C. intervene
D. interfere

[单项选择]______got in the wheat than it began to rain heavily.


A. No sooner have they
B. No sooner they have
C. No sooner had they
D. No sooner they had

[单项选择]It is believed that efforts at resuscitation are useless when ______.

[单项选择]

There have been many great (21) . The first great invention was one that is still very important to day--the wheel. This made it easier to carry (22) things and to travel long distances.
In the early 1800s the world (23) to change. There was little unknown land left in the world. People did not have to explore much any more. They began to work instead to make life belier.
In the second half of the 19th century many great inventions were made. Among them were the camera, the electric light and the radio. These all became a big part (24) our life today.
The first part of the 20th century saw more great inventions: the helicopter in 1909, movies with sound in 1926, the computer in 1928, and jet planes in 1930. This was also a time (25) a new material was first made. Nylon came out in 1935. It changed the kind of clothes people wore.
The middle part of the 20th century brought new ways to help people (26) disea
A. discoveries
B. creations
C. invention
D. inventions