环境污染对人体造成的慢性损害主要表现在职业病上。
参考答案：对
a和b的最大公因数是1，最小公倍数是[ ]
A．a·b
B．a+b
C．a
D．b
We arranged to meet at 8:00, but she never ______.
A．turned down
B．turned off
C．turned over
D．turned up
