Idiomatic phrasal verbs: 'pitched in' vs. 'pitched on'

[Gelly]

English Language Tests, Intermediate level

ESL/EFL Test #197 "Phrasal Verbs (P to R)", question 5

The whole community ......... to make the playground safe and aesthetic.

(a) pitched on
(b) pitched in
(c) pitched over

English Language Tests, Intermediate level

ESL/EFL Test #197 "Phrasal Verbs (P to R)", answer 5

The whole community pitched in to make the playground safe and aesthetic.

Correct answer: (b) pitched in

Your answer was: incorrect
The whole community pitched on to make the playground safe and aesthetic.
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why couldn't i use pitched on?

Gelly

[Mister Micawber]

.
The idiomatic phrasal verb for 'cooperate' is pitch in, not pitch on. The latter is not a phrasal verb.
.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mr. Micawber