搜题请搜索小程序“爱下问搜题”
问题 单项选择题 B型题

可以通过胎盘引起胎儿中毒的有害金属是（）

A.汞

B.镉

C.铅

D.铝

E.铜

答案

参考答案：A

解析：1.甲基汞可通过血脑屏障、胎盘屏障和血睾屏障，造成胎儿的汞中毒。 2.镉中毒主要损伤肾脏、骨骼和消化系统。由于骨钙析出而发生骨质疏松和病理性骨折。

完形填空

根据首字母或所给的中文提示，写出各单词的正确形式

You are so t  小题1:at night, but you can’t sleep. Here are some good i  小题2:. First, you s    小题3:be in a quiet room. That’s important. You should put your f   小题4:in some warm water   b   小题5:you go to bed, and that’s a traditional way. You should have a glass of milk. It’s g    小题6: for sleeping. You should think you are in a beautiful place. It is very quiet there and there are many trees and you walk slowly. That s  小题7:like a good idea. It can help you to sleep soon.

Sleeping is important to our  h   小题8: .Don’t be stressed out. Go to bed  e    小题9:, eat more vegetables and  do some  e 小题10:. And everyone will have a good sleep.
查看答案
材料分析题

材料一：发达国家科学技术对国民生产总值增长的贡献率：

  

时期20世纪初20世纪中期 20世纪末
 科技贡献率5%-10%  50% 70%-80% 
   

材料二：据《经济参考报》报道，在中国的发明专利申请中，来自国外的占82%，且技术含量高；来自国内的占18%，且技术含量低。有关人士表示，“82%：18%”凸显目前中国自主知识产权所面临的困境。请回答：（1）材料一、材料二分别说明了什么？                                                                                                                                 （2）要解决我国面临的困境，关键是什么？为什么？                                                                                                                                 

查看答案