问题
问答题 简答题
避免用于敏感作物和作物的敏感期
答案
参考答案：
因为不同作物和品种对氯的敏感性和忍耐性有很大差异。对氯敏感的作物称为忌氯作物，有烟草、茶叶、柑橘、葡萄、西瓜、马铃薯、紫云英等，一般不施或严格控制含氯化肥施用量。
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避免用于敏感作物和作物的敏感期
参考答案：
因为不同作物和品种对氯的敏感性和忍耐性有很大差异。对氯敏感的作物称为忌氯作物，有烟草、茶叶、柑橘、葡萄、西瓜、马铃薯、紫云英等，一般不施或严格控制含氯化肥施用量。
We are all busy talking about using the Internet, but how many of us know the history of the Internet? Many people are ___36___ when they find that the Internet was set up in the 1960s. At that time, computers ___37___ large and expensive. Computer networks didn’t work well. If one computer in the network ___38___ down, the whole network stopped. ___39___ a new network system（系统）had to be set up. It should be ___40___ to be used by many different computers. If part of the network was not working, ___41___ could be sent through another part. In this way computer network system would keep on ___42___ all the time. At first the Internet was only used by the government, but in the early 1970s, universities, hospitals and banks were allowed to use it too. However, computers were still very expensive and the Internet was difficult to use. By the start of the 1990s, computers became cheaper and ___43___ to use. Scientists had also developed software that made “surfing”（浏览）the Internet more convenient. Today it is easy to get on-line and it is said that millions of people use the Internet every day. ___44___ e-mail is more and more popular among students. The Internet has now become one of ___45___ parts of people’s life.
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