lot是什麼意思解釋一下

例句：

I learned a lot from my father.

我從父親那裏學到了許多東西。

A lot hangs on this decision.

很多事情都取決於這一決定。

I've got a lot of commitments.

我有很多要做的事。

He's made a lot of new friends.

他交了許多新朋友。

The charity does a lot of good.

這家慈善機構做很多善事。