Correct my English: It was a challenge to keep them amused

[Laroche]

Hi,

I came across a sentence in the Oxford dictionary. I am curious if the same sentence is correct if expressed in some other ways. Here they are:

It was a challenge keeping them amused (oxford dictionary)

It was a challenge to keep them amused (can it also be put this way?)

It was challenging keeping them amused (can it also be put this way?)

It was challenging to keep them amused (can it also be put this way?)

[Alan]

Hi,

Yes, they are all acceptable variations.

Alan
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