pitch in

verb

(transitive, intransitive, idiomatic) To help out; lend assistance; contribute; to do one's part to help. / To begin briskly.

Can you pitch in and help with the cleaning?

意味（1）

(transitive, intransitive, idiomatic) To help out; lend assistance; contribute; to do one's part to help.

If we all pitch in, we can raise enough money for the renovation of the church.

意味（2）

To begin briskly.