有用 in English:

Avail yourself of this opportunity.

He attempted to climb the fence to no avail.

All my efforts proved of no avail.

without avail

He was glad to avail himself of any means to succeed in life.

I tried to shut out the noise of the traffic, but it was of no avail.

We have discussed the problem several times but to no avail.

They searched high and low for the missing boy but to no avail.

Talk will not avail without work.

The anxiety of sellers to avail of prices which look very high.

Crying is of no avail.

The doctors' efforts to save the child were to/of no avail.

They drilled on, desperately trying to pick up the vein again--all to no avail.

Our best efforts did not avail

We searched the whole area but all to no avail. Robbie had disappeared.