题干

下列对有关实验的叙述,正确的是(  )

A:在观察洋葱细胞有丝分裂实验中,将已经解离、漂洗、染色的根尖置于载玻片上,轻轻盖上盖玻片后即可镜检

B:甲基绿是将活细胞中线粒体染色的专一性染料

C:在叶绿体色素提取实验中,研磨绿叶时应加一些有机溶剂,如无水乙醇等

D:检测试管中的梨汁是否有葡萄糖,可以加入适量斐林试剂后,摇匀并观察颜色变化

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答案(点此获取答案解析)

C

同类题4

根据短文内容,选择正确答案。

    Open today's newspaper. What do you see? Ads! Look through a magazine. More Ads! Turn on TV, still more ads! Everywhere you look, someone has something to tell. Here are some ways ads get us to buy.

    Some ads use famous people. Stars are paid to sell a product. Think about it. Do they really know about medicine? Do they know about soft drink? These people may be famous. But they may not know about what they are selling.

    Some ads make you think you're getting the word of an expert. They say, "Doctor said." A man in a white coat comes on TV. He looks nice. "I use bright and white," He says. This man looks like a doctor. But he is an actor. He has been paid to sell this product.

    Does soap have anything to do with a pretty child? Not much. But ads may show their product with something nice such as the sun, the flowers and so on. Such an ad is about feelings rather than facts.

    Ads are full of strong words, and words like "new" and "improved" have power. They can help a produce sell. The soap may be called "Spring Rain". A car may be called "Tiger". Strong words work on our feelings.

    Some ads make promise. But can they keep them? No.

    Some ads use our fear of being too late. "Buy now!" They say, "Selling ends soon." Check to see if this is true. Don't hurry. Take time to think.

    All ads hope we will buy something, do something, or think in a certain way. Know what ads are doing. Ask questions to yourself. Don't let their words and pictures fool you.