泰山在地质构造上属于（ ）
A：背斜
B：向斜
C：地堑
D：地垒
These fans arrived very early. They could see their favorite stars. （合并成一个句子）
These fans arrived very early ____ they could see their favorite stars.
已知函数f（x）的导函数为f′（x），满足f（x）=2xf′（2）+x3，则f′（2）等于（ ）.
—I've got a headache.
—No wonder.You in front of the computer too long.
