仙人掌生活在缺水的沙漠，叶子退化成刺状，没有光合作用的功能。（　）

 根据对话内容，用方框中所给单词的适当形式填空，每词限用一次。

water    no    Earth    it    for

Bill: I saw a great programme on TV about space yesterday evening.
Tony: What is ____ about?  
Bill: Scientists have discovered ____ on Mars.
Tony: Really? That's very fantastic. Have they discovered life on Mars?
Bill: Well, they're looking____  life but they haven’t found anything yet.
Tony: I know there's ____ life on the moon.
Bill: Yes, that's right. So far there's only life on ____ .
Tony: Are we alone with so many stars in the universe?
Bill: I am interested in it, so I want to be a scientist when I grow up.
Tony: I wish you will.

把烧红的钢件放到冷水中，会听到“嗤”的一声，同时看到水面立即会出现“白气”，这一物理现象中，水先后发生的物态变化是 ____和 ____

已知数列{a_n}中，a_n+1=3S_n，则下列关于{a_n}的说法正确的是（　　）

（多选）一定温度下，对可逆反应A（g）+2B（g）⇌3C（g）的下列叙述中，不能说明反应已达到平衡的是（   ）