题目内容：

Directions: Complete the following passage by using the sentences in the box. Each sentence can only be used once. Note that there are two sentences more than you need.

A period of important agricultural development began in the early 1700s in Great Britain and the Low Countries(Belgium, Luxembourg. and the Netherlands, which lie below sea level). 1.

One of the most important of these developments was an improved horse-drawn seed drill invented by Jethro Tull in England. Until that time，farmers sowed seeds by hand. Tull’s drill made rows of holes for the seeds. By the end of the 18th century, seed drilling was widely practiced in Europe. Many other machines were developed in the United States. 2. At about the same time，John and Hiram Pitts introduced a horse-powered thresher (脱粒机) that shortened the process of separating grain and seed from straw. John Deere’s steel plow (犁), introduced in 1837, made it possible to work the tough soil with much less horsepower.

Along with new machines，there were several important advances in selective farming. By selectively breeding animals (breeding those with desirable traits), farmers increased the size and productivity of their livestock. Plants could also be selectively bred for certain qualities. In 1866, Gregor Mendel’s studies in heredity (遗传) were published in Austria. 3. His work paved the way for improving crops through genetics.

New crop planting methods also evolved during this time. Many of these were adopted over the next century or so throughout Europe. For example，the Norfolk four-field system, developed in England，proved quite successful. It involved the yearly rotation (轮作) of several crops, including wheat, turnips, barley, clover, and ryegrass. 4. Moreover, this method enabled farmers to grow enough to sell some of their harvest without having to leave any land unplanted.

Not all parts of the world benefited from these developments instantly. However，farmers in other parts such as Australia and Africa continued to use old ways of agriculture for a long time.

A.This could add desired nutrients to the soil thanks to the rich variety of crops.

B.Over centuries, the growth of agriculture contributed to the rise of civilizations.

C.In experiments with pea plants, he learned how traits were passed from one generation to another.

D.In the 1830s Cyrus McCormick’s harvesting machine helped modernize the grain-cutting process.

E.This helped to produce extra food to trade for other goods and allowed people to work at other tasks.

F.New agricultural inventions dramatically increased food production in Europe and European colonies.