Participle or gerund
Mr Garrett is interested in .....(learn) Russian
He is very good at... (learn) languages

Infinitive or gerund
Can you show me how... this computer program? (Use)
Would you mind. ..the first three chapters? (Prepare)

Mr Garrett is interested in .....(learning) Russian.

He is very good at... (learning) languages.

Can you show me how... this computer program? (to use)

Would you mind. ..the first three chapters? (preparing)