——Would you like to go shopping with me?——I'd love to, _____I can't. I have a lot of homework to do.
A:or
B:but
C:so
先化简,再求值:(2x+5)(2x﹣5)+2x(x+1)﹣3x(2x﹣5),其中x=2.
下列物质属于纯净物的是 ( )
6712= ____ 217= ____ 1029= ____ 3113= ____
11511= ____ 3913= ____ 378= ____ 234= ____