ненадежный Anglais:

I won’t ask Colin for help because he is unreliable.

Frankly speaking, he is an unreliable man.

he’s lazy and unreliable

That car's so unreliable it'll never make it to London.

Do not count on him, he’s unreliable.

Moran has proven himself to be extremely unreliable.

It shows what an unreliable person he is.

He is a bit unreliable. (don't do what they say they will do).

He's a dishonest unreliable man so don't trust him

Jane is renowned for being unreliable, so expect her to be late.

He's totally unreliable as a source of information.

Emily cannot be trusted. She often cancels things at the last minute or just doesn't turn up. She is unreliable.

It’s such an unreliable bus service – I never know what time I'll arrive at the office!

unreliable witness, evidence

Our experiment has revealed that his report was unreliable.

Her health remained precarious, despite the treatment. a precarious mountain trail

a precarious situation

People smoke to relax and forget their cares, but ironically, in terms of health risks, smoking is far more precarious than either mountain-climbing or skydiving.

The museum is in a financially precarious position.

The world is a precarious place.

Your position is precarious

The lorry was lodged in a very precarious way, with its front wheels hanging over the cliff.

Frankly speaking, he is untrustworthy.

Don't have anything to do with him. He is completely untrustworthy.