J1M型计量泵传动箱内要及时更换机油，加油量以加到油标的（）为宜。
A.1／3处
B.满刻度处
C.中心线处
D.2／3处
参考答案：C
试述医疗设施中心化的优点。
I don't think teenagers should be allowed to do homework with friends, because they are ______. [ ]
A. not enough quiet
B. not quiet enough
C. too not quiet
D. enough not quiet
