This closes the circuit and turns the transistor on.

这两个电极就会形成通路。

So by manipulating the control wire, one could open or close the circuit.

因此通过操作控制线路我们就可以打开或闭合电路。

Additionally, it has a closed circuit television camera to keep an eye on the placement of the slung load in order to defend itself against ballistic missiles.

此外，它还有一个闭路电视摄像机来监视悬挂负载的位置，以防御弹道导弹。