购物大姐常说“便宜没好货”，她这句话的意思是：“不便宜”是“好货”的（  ）

制约新疆农业生产的主要因素是（　　）

A～G是几种烃的分子球棍模型（如图），据此回答下列问题：

（1）常温下含氢量最高的气态烃是　 ____　（填字母）．

（2）能够发生加成的烃有　 ____　种，一卤代物种类最多的是　 ____　（填写字母）．

（3）写出F发生硝化反应的化学方程式 ____

阅读理解
     John is a paper boy. He delivers（投递）newspapers to different houses in his street every day. He has about 80 customers（客户）. Half of his customers only take the newspapers on weekdays, and about half take the newspapers on weekdays and on Sundays. Two of John’s customers only take the newspapers on Sundays.
   John has to get up at 4：30 every morning to deliver his newspapers. It takes longer to deliver the newspapers on Sundays. The Sunday newspapers are twice as heavy as those on weekdays.
   John is saving his money to buy a new bicycle. He is also saving money for college （大学）. He has already saved 500 dollars

阅读材料，回答问题。
材料一：匈奴人失去河西，损失重大，唱到：“失我祁连山，使我六畜不再息（意为生长繁盛），失我焉支（胭脂）山，使我嫁妇无颜色（不能打扮得漂亮了）！”
材料二：史书记载，昭君和亲后，边关的城门很晚才关闭，处处都是放牧和贸易的牛马，好几代人再听不到报警的狗叫声，老百姓再也没有战争之苦。