单项选择题

A. She was invited only for the weekend.
B. The weather was too hot.
C. She had an appointment.
D. She has schoolwork to do.
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单项选择题
A. To prepare students for the next reading assignment.B. To provide background information for a class discussion.C. To review material from a previous lesson.D. To prepare for a quiz on chapter six.
A. To prepare students for the next reading assignment.
B. To provide background information for a class discussion.
C. To review material from a previous lesson.
D. To prepare for a quiz on chapter six.
填空题
Scientists in India have discovered a way to make bamboo plants produce flowers in laboratory. The British publication Nature recently reported the historical event. In the wild it call take (26) 120 years for some kinds of bamboo to flower, and after the plant drops its seeds it dies. The bamboo plant is used in many different ways. But (27) it takes so long to produce seeds, scientists never consider it a traditional farm crop. The recent breakthrough in India may change that. The research was done at the National Chemical Laboratory in India. Three scientists cut 200 pieces from two different kinds of bamboo plants, each was a few (28) long. The tiny cuttings were placed in the (29) of coconuts milk, plant-growth hormone and other nutrients. Just a few weeks later, flowers began to appear. They were the same size as flowers on (30) grown bamboos. Two weeks after that the plants began to produce seeds. In the wild, it will take 30 years for these kinds of bamboos to (31) and (32) seeds. One of them had not put the bamboo seeds in soil, but he believes they will produce plants. The Indian scientists now are planning experiments to (33) if they can improve the bamboo (34) the techniques of genetic engineering. Bamboo reproduces in two ways. It flowers and produces seeds. It also produces new growth from its roots. Bamboo shoots are (35) and planted in the field again. Farmers harvest the leaves. They feed them to their animals.
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