正确答案:

题目：经市场调查，某种优质西瓜质量为（5±0.25）kg的最为畅销.为了控制西瓜的质量，农科所采用A、B两种种植技术进行试验.现从这两种技术种植的西瓜中各随机抽取20颗，记录它们的质量如下（单位：kg）：

解析：（1）依次为16颗，10颗

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举一反三的答案和解析：

[单选题]空气是一种宝贵的资源，空气中体积分数约占21%的是

氧气

[单选题]下列关于催化剂的说法正确的是（     ）

催化剂能改变化学反应速率

[单选题]CThey wear the latest fashions with the most up-to-date accessorise(配饰)。Yet these are ginrls in their teens or twenties but women in their sixties and seventies.A gengration which would once only wear old-fashioned clothes is now faouring the same high street looks worn by those half their age.

the price of clothes has generally fallen by 70%

[单选题]5． —Why do you like Beijing Opera?—Because I can _______a lot _________Chinese history．

learn; about

解析：5.A 【解析】learn a lot/much about sth.意为“对某事了解很多，得知有关某事的很多东西”。

[单选题]7．

with

解析：7．A【解析】a story with pictures配有插图的故事． with表示前面被修饰的名词具有某种特征。

[单选题]3．Why not_________your position?

consider changing

解析：3．D【解析】why not+do表建议，consider后接动词一 ing形式作宾语。