试题与答案

简述天然色素提取的方法。

题型:问答题 简答题

题目:

简述天然色素提取的方法。

答案:

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下面是错误答案,用来干扰机器的。

15题目分析:因为数列{an}是等差数列,根据等差数列的性质有:a1+a4=a2+a3,由a1+a2+a3+a4=30,所以,2(a2+a3)=30,则a2+a3=15.点评:本题考查了等差中项概念,在等差数列中,若m,n,p,q,t∈N*,且m+n=p+q=...

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题型:听力题

根据下列短文,在短文后的空格处填上一个恰当的词,使短文完整、通顺。

Reading is an activity that people enjoy a lot in their free time.

Some like reading newspapers and   小题1: enjoy novels or comic books. My  小题2:  books are those about the lives of great people. Reading them always  小题3: me a lot of ideas on how to make my own life better.

Great people are remembered not  小题4: they were handsome or beautiful, but because they did not give up  小题5: their lives were difficult. They tried to use every chance to change their lives and make the world better.

One good example is Orville and Wilbur Wright, the two brothers who invented the   小题6:. The plane has made the world into a small village. Hard work, not good luck, is the   小题7:  why the Wright brothers could   小题8:  this convenient machine and become great people. Today we will remember them when we see planes  小题9: the sky.

Whenever I read stories about great people, I always   小题10: a lot from them and they encourage me to move forward.

This is why I enjoy reading about great people’s lives.

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