工业上用分离液态空气的方法制取氧气，是利用了液氮和液氧的____ 不同．

Monday, May 7, Sunny

    I had a pretty good time in Beijing last weekend with my parents and my brother.

    We went to Beijing by train on Friday night and got there on the morning of Saturday. We went to Tian'anmen Square first. There were many people there. We watched the national flag(国旗)go up. Then we went to the Palace Museum. My parents liked it very much, but I thought it was kind of boring. After lunch, we visited the Great Wall. When we got to the Great Wall, it started to rain. The rain made the mountains look very beautiful. We played on the Great Wall and took some photos. On Sunday morning, we visited a Beijing Hutong. Then after buying some things in Wangfujing Street in the afternoon, we went back home. We really enjoyed ourselves.

⑴题完成句子；(2)～(3)题简略回答问题；(4)题找出并写下全文的主题句；(5)题将文中画线句子译成汉语。

人类的双眼皮是由基因A控制，单眼皮由基因a控制，请根据下列简单遗传图解回答相关问题．