题干

下列有关酶的正确叙述是
①是有分泌功能的细胞产生的 ②有的从食物中获得,有的在体内转化而来 ③凡是活细胞,一般都能产生酶 ④酶都是蛋白质 ⑤有的酶不是蛋白质 ⑥酶在代谢中有多种功能 ⑦在新陈代谢和生长发育中起调控作用 ⑧酶只是起催化作用

A:①②⑤  

B:①⑤⑧ 

C:③⑤⑧

D:①③⑤

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答案(点此获取答案解析)

C

同类题3

阅读下列短文,从每题所给的几个选项中,选出最佳选项。

B

    When was the last time you gave or received a hug? Do your parents hug you before you go to school? In Western countries, it is quite common to greet close friends or relatives with a hug.

    You might hug your teammates after winning a basketball game. If one of your friends is having a bad day, you can hug them to cheer them up. Friends who haven't seen each other for a long time will usually hug each other when meeting.

    Of course, people in different countries have different opinions when it comes to hugging. After coming to China, I've noticed that people are generally more reluctant (不情愿的) to hug than they are in my home country, the US.

    My Chinese friends told me that hugging is considered to be very intimate (亲密的) in their culture. It usually only happens between people who are really close to each other, like couples. Chinese people don't usually hug in public, either.

    But people's attitudes (态度) towards hugging can also change. I remember watching a video story about a “hugging party” that was held in Shanghai. A local artist held the party, inviting strangers and asking them to hug each other.

    The Chinese participants (参与者) clearly looked uncomfortable. However, after the party, several of them changed their minds. They decided that hugging doesn't have to be awkward (尴尬的) and can actually be quite nice. So next time you see your mom or dad, give them a hug –see how it makes you feel.