Couldn't

I couldn't have done it without you. Thank you.

I couldn't say when exactly in my life it occurred to me that I would be a pilot someday.

I couldn't call you; the telephone was out of order.

He couldn't be good for you.

It was too bad you couldn't come.

It's a pity that you couldn't come.

The bridge couldn't sustain the force of the strong current and collapsed.

I couldn't make myself understood in a foreign country.

I couldn't sleep well because it was noisy outside.

Everybody was disguised, so I couldn't tell who was who.