隧道工程喷射混凝土施工，说法正确的是（）。

A.工作风压应随输送管距增加而降低

B.喷嘴与作业面的距离应小于0.5m

C.喷嘴水压通常应比工作风压大

D.喷射混凝土骨料含水率应大于8%

In our school, students are            according to how much they know and how old they are.

A．classified

B．combined

C．listed

D．made