①代数式3x2﹣3x+6的值为9,则x2﹣x+6的值为____ ;
②比较大小:tan62°﹣cot61°____ 1(可用计算器).
补全下面的对话。
A.Size 8,please.
B.These shoes are nice.
C.I will take them.
D.How much are they?
E.Here you are.
A:Can I help you?
B:Yes.____Can I try them on?
A:Of course.
B:____
A:OK.____
A:$50.
B:Here is the money.____
科学技术是( )①先进生产力的集中体现 ②先进生产力的重要标志 ③创造财富的源泉和技术支撑 ④第一生产力
读“河西走廊地形剖面图”,完成下列题目: