a sum of money
I will lend him a sum of money.
a tablespoon of salt
You should add a tablespoon of salt.
a clap of thunder
A clap of thunder woke me up.
a jar of honey
I went to the grocery store to buy a jar of honey.
a drop of rain
There still was not a drop of rain.
a ray of sunshine
A rare ray of sunshine in these rainy autumn days.
