before top dead center
在上死点前在上止点前
before bottom center
下死点前在下止点前
after top center
上死点后在上止点后
So the exhaust valve opens before BDC and closes after TDC.
因此排气门在下止点之前打开，在上止点之后关闭。
So far, the focus has been on fiscal discipline.
到目前为止，其重点都是放在财政纪律之上。
The teacher calls over the children's names before the class begins.
教师在上课前点名。
at nine o'clock. I must go to bed before half past ten tonight.
9 点。我今晚必须在10 点半前上床睡觉。
The Bore is the diameter of the cylinder. The stroke is the distance the piston travels from BDC (Bottom dead center) to TDC(top dead center). The Bore is always mentioned first.
内径指的是气缸的直径;行程是活塞从下止点运行到上止点的距离。表述时,内径总是写在前面。
after bottom dead center
下死点后在下止点后
The cook smeared some oil on his hands before he made the cake.
厨子在做点心以前在手上抹了些油。
I don't suppose that I'll be back until nine in the evening .
我看我在晚上九点之前回不来。
Passengers must board the ship by 6 p.m.
旅客必须在下午六点钟以前上船。
Please see to it that the children go to bed by 9 o'clock.
请务必使该子们在9点之前上床睡觉.
Whoever thinks of going to bed before twelve o'clock is a scoundrel .
凡是想在十二点之前上床的都是坏蛋。
point where the hairline meets the midpoint of the forehead.
前额上头发聚在一起的中点。
at some point or distance before a goal is reached.
在达到目标之前的某个点或者距离上。
Each day before class begins, the teacher always calls the roll.
老师总是在每天上课前点名。
Every day before class begins the teacher always calls the roll.
每天在开始上课前，老师经常要点名。