随着人们消费观念的不断变化，利用信用卡的透支功能来满足自己消费需求的“负翁”悄然出现。对于“负翁”现象，下列理解正确的是（    ）

① Why do you like spring? ____     A. I went home at 9：20.

② When did you go home last night?____     B. They are thirty “five yuan”

③ Was there a library in your school before? ____     C. Because I can fly kites.

④ How much are your pants?  ____     D. It’s big and bright.

⑤ What’s your new room like?   ____     E. No, there wasn’t.

已知关于x的方程x²-kx-3=0的一个根为3，则k的值为（   ）

生活中我们要坚持五用原则：弃用— 一次性产品；代用—自备购物袋；节用—节约能源资源；慎用—纸张；重用—废物回收再利用。“五用”共同体现了（   ）