题目

下面对有关实验的叙述中正确的是（ ） A . 在减数分裂模型的制作中，用两种颜色的橡皮泥表示姐妹染色单体 B . 剪取根尖分生区，经染色后在光镜下可看见有丝分裂各时期 C . 在光镜下的高倍镜下观察黑藻的装片，可观察到叶绿体的结构 D . 马铃薯块茎捣碎后的提取液遇双缩脲试剂可以显紫色 答案：DFor many years, the school students have to finish some homework during their winter and summer holidays. But with the fast development of the Internet, some students have found a new way to deal with their homework recently. Instead of finishing their homework by themselves, they ask the Internet for help.Since most of the holiday homework is the same from school to school, this makes it possible for some people to sell the homework answers on the Internet. Usually one must pay about 50 to 100 yuan for the answers for one subject of the homework. A survey shows that 90% of the students complain their homework is too much and they don’t want to do it by themselves.To solve the problem, some schools have stopped using the standard homework and turned to other forms of homework. As for students, they must remember “No pains, no gains”. If today they pay for their homework answers, perhaps one day they will pay more for their laziness（懒惰）.1. Some students deal with their holiday homework by _______.A. copying their classmates’ homeworkB. doing their homework by themselves every dayC. doing nothing at allD. buying homework answers through the Internet2.The price of the answers for one subject is _______.A. 90 yuan B. about 100 yuanC. about 50 yuan D. about 50 to 100 yuan3. From the passage We can know _______.A. the students can’t finish their homeworkB. Internet is very useful but has some disadvantageC. we can buy anything we want through the InternetD. all the students are very lazy