Gerund vs infinitive

Molly is good at ... the electric guitar.

• play

• to play

• playing

My baby brother is one year old and he's learning ... on his own.

• walk

• to walk

• walking

I'm used to ... the room with somebody.

• to share

• share

• sharing

Would you apologise for ... rude?

• to be

• be

• being

Yesterday I helped my sister ... her maths homework.

• to do

• do

• doing

Tell me when you're ready ..., okay?

• to start

• start

• starting

I'm always the first ... the teacher's questions.

• to answer

• answer

• answering

Frank promised ... me tomorrow.

• to call

• call

• calling

We really enjoy ... in the mountains.

• to hike

• hike

• hiking

I was sad ... the news.

• to hear

• hear

• hearing