问题 单项选择题

阅读以下文字,回答下列问题。

  早在19世纪,人们就开始研究光活化现象。1888年,马卡西提出光可提高生物碱对种子、植物和两栖动物卵的毒性。20世纪初,人们又研究了叮啶、荧光素等染料在光照下的杀虫作用。到70年代,约荷等人又研究了卤代荧光素对家蝇的光动力作用,将光活化农药的研究推向一个新的高潮。

  研究中人们发现,一些物质平时并无毒性,但进入生物体内在光诱导的氧化作用下,会产生毒性,它们在自然界中会迅速降解变为无毒物质。光动力作用的过程十分复杂,影响该过程的因素很多,其最终产物也可能是多样化的。因此,光活化农药在理论和应用上,还有许多问题有待研究。光动力作用进攻的目标有生化组合物、生物膜和酶。可被光敏化氧化的物质包括蛋白质、糖、类固醇、脂肪酸、硫化物等。光敏化氧化将改变或破坏上述物质正常的生物功能,对生物有机体产生毒害。

  近年来,光活化农药的优点和应用前景已引起人们的广泛关注。人们已发现了一些较有效的光敏化剂,它们可能被应用于光活化农药制剂中。例如赤藓红B,能有效地对家蝇、大蚁、象鼻虫、家蚊、蝴蝶、夜盗虫起毒害作用,是目前实现商品化的少数光活化农药中较典型的一种。

光活化农药起作用及降解过程示意图中填在括号内错误的一项是()

A.进入生动体

B.光动力作用

C.氧化作用

D.回归大自然

答案

参考答案:C

听力题

根据短文内容及首字母提示,补全空格内单词,使短文完整、通顺。

Some years ago, I went to Australia for a meeting with my friend, Chris. We decided to drive across the country to Brisbane after the meeting ended. The drive was going to take four days and most of it was across the desert, so we had to take food, water, and extra gas(汽油) w  1  us.

The first day was a lot of fun as we were excited and laughing at each other’s jokes. By the third day of driving in the seemingly endless desert, we began to get b  2 . We had been quiet for a few hours when Chris found some kangaroos in the distance. We were b  3  excited and decided to get a closer look. Chris speeded up to

c  4  up with the kangaroos. We got closer and closer, and Chris was doing 110 kilometers per hour. We were very close to the kangaroos—too close—when we heard a loud BANG!

Chris s  5  the car and we got out. Behind the car was a larger kangaroo l  6  completely quiet on the ground. Chris went over to the kangaroo and put his baseball cap on its h  7 . He took off his sunglasses and put them on the kangaroo and did the same with his jacket. Then he put his arm a  8  the kangaroo and told me to take a photo of them together. I was still surprised, but I took out my c___9___. While I was ready to take photos, I saw the kangaroo move. It suddenly woke up, looked at Chris, and jumped away into the distance before we could do anything.

I started laughing but Chris looked very serious. He said his wallet and passport were in the jacket. I started laughing even harder. I stopped laughing, h  10 , when he said that our car keys were also in the jacket!

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