这辆车有一个严重的设计缺陷。

The car has a serious design ___fault.

他们认为火灾是由电气故障引起的。

They think the fire was caused by an electrical ___fault.

我走出房子，看到其他房子也没有灯，所以不是电气故障。

I went out of the house and I saw that the other houses had not got any lights, so it was not an electrical ___fault.