下列计算,正确的是( )
A:4=±2
B:5-3=2
C:2×5=7D
D:12÷2=6
设集合U={x|x<3},A={x|x<1},则CUA=( )
——Would you mind ______ your bike?——No, not at all. I'll put it under the tree right away.
对下列物质在氧气中燃烧的实验现象描述正确的是( )