问题 单项选择题 B型题

机体食用牛奶后出现腹胀、腹痛、产气增多等症状的原因可能是()

A.体内缺乏葡萄糖6-磷酸酶

B.红细胞中缺少单加氧酶

C.食物中含有苯胺

D.小肠黏膜乳糖酶缺乏

E.体内缺乏半乳糖激酶

答案

参考答案:D

解析:小肠黏膜乳糖酶缺乏的人,在食用奶或奶制品后,奶中乳糖不能完全被消化吸收而滞留在肠腔内,使肠内容物渗透压增高、体积增加,肠排空加快,使乳糖很快排到大肠并在大肠吸收水分,受细菌的作用发酵产气;轻者症状不明显,较重者可出现腹胀、肠鸣、排气、腹痛、腹泻等症状,医生们称之为乳糖不耐受症,故1小题选D。体内如缺乏葡萄糖6-磷酸酶,吃蚕豆后会造成血液中的红细胞被破坏,引起过敏症,严重者出现呕吐、贫血、黄疸、肝脾肿大、腹痛等过敏现象,故2小题选A。

阅读理解

阅读对话,判断句子的正(T)误(F)。

     (Chen Hong and Peter Johnson are talking about two American cities:  New Orleans and San

       Francisco. )

Peter: New Orleans and San Francisco are my favorite cities. Have you ever been there?

Chen: No. I've been to neither of them.

Peter: Well,  New Orleans is one of the most interesting cities in the United States. It has a French

          Quarter (地区 ), with narrow streets and little old shops.  Many of the shops and restaurants are

          French.

Chen: There's a lot of jazz (爵士) music in New Orleans, isn't there?

Peter: Yes. You can hear wonderful jazz there.

Chen: And San Francisco?

Peter: It has lovely views and one of the most beautiful bridges in the world—the Golden Gate Bridge.

          It's   a very hilly (多山丘的) city. The hills are in the middle of the town, so you have to walk up

         and down hills when you go anywhere. When you drive, your car needs good brakes (刹车).

Chen: Do you have to drive? Can't you take buses?

Peter: Well, most visitors to San Francisco ride in cable cars (缆车). A cable car goes on tracks (轨道),

          and a strong cable pulls it up the hills.

Chen: That doesn't sound very safe.

Peter: Don't worry. Hundreds of people ride in cable cars every day.

1. Chen Hong has been to San Francisco.

2. You can hear wonderful jazz in New Orleans.

3. The Golden Gate Bridge is in San Francisco.  

4. When the tourists visit San Francisco, most of them drive cars.

5. There are lots of hills in New Orleans.

名词解释