Then the intake valve closes, and an exhaust valve opens.

然后进气阀关闭，打开 排气阀。

Then, an intake valve opens, allowing the steam into the engine.

然后，进气阀打开，让 蒸汽进入发动机。

Last step, exhaust valve opens, piston travels up, it forces that spent burnt gases out your exhaust pipe, out into the atmosphere.

最后一步，排气阀打开，活塞向上移动，它迫使燃烧过的气体从排气管向下进入大气。

The idea is you have the valve open and stick the wide end over a hole.

操作方法就是打开阀门，用大头封住洞口。

The valves open as blood moves toward the heart and then close to prevent the backward flow of blood.

当血液流向心脏时，瓣膜打开，然后关闭，以防止血液回流。

Now after both the aortic and pulmonary valves have shut down, the atrioventricular valves open again, letting the cycle start all over again.

当主动脉瓣和肺动脉瓣都关上后，房室瓣再次打开，使心动周期重新开始。

When blood is forced out of the ventricles, the semilunar valves open wide, allowing the blood to pass into the arteries.

当血液被迫流出心室时，半月形瓣膜会张开，从而使血液进入动脉。

Right after the S1 sound, the aortic and pulmonic valve open up allowing blood to get pushed out to the body and this period of time is called systole.

在S1之后，主动脉瓣和肺动脉瓣打开，分别使得血液流入身体各组织以及肺部，这段时期叫做心脏收缩期。

Right after the S2 sound, the tricuspid and mitral valves open back up allowing blood to fill up the ventricles again and this period of time is called diastole.

在S2之后，三尖瓣和二尖瓣打开；让血液再次充盈心室，这段时期叫做心脏舒张期。

Then, an intake valve opens, allowing the steam into the engine. The steam expands and moves a piston outward – that’s the work done by the engine.

然后，进气阀打开，让蒸汽进入发动机。蒸汽膨胀并向外移动活塞——这就是发动机所做的功。

When a valve opens, blood flows in one direction into the next chamber. And when it closes, that's it — no blood can just flow back into the chamber it just left.

当瓣膜打开时，血液从一个方向流向下一个腔室。当它关闭时，就这样——没有血液可以流回它刚刚离开的腔室。

Then, when there's high demand for electricity, valves open, releasing the stored energy by letting water flow downhill to power 6 giant turbines that can generate 3 billion watts of power for 10 hours.

然后，当电力需求量大时，阀门打开，让水流下坡释放储存的能量，为 6 个巨型涡轮机提供动力，这些涡轮机可产生 30 亿瓦的电力，持续 10 小时。