企业获准认证的有效期一般为（）年。
A．1
B．3
C．5
D．10
参考答案：B
职业病可以分为哪些类别?
--I have _____ finished my homework. What about you?
--I finished it ______
A．just, just
B．just now, just
C．just, just now
D．just now, just
