那个城市的公共交通经常不可靠。

Public transportation in that city is often ___unreliable.

法庭认为证人的证词不可靠。

The witness's testimony was deemed ___unreliable by the court.

他是个不可靠的朋友，因为他经常食言。

He is an ___unreliable friend because he often breaks promises.