使正常的粪便呈褐红色的色素物质是（）
A.粪胆素
B.尿胆素原
C.胆红素
D.胆绿素
E.氧化酶
参考答案：A
8、When and where to go for the on-salary holiday ______ yet.
A．are not decided
B．have not been decided
C．is not being decided
D．has not been decided
5050千克=______吨．
