You didn't underline anything, so we cannot know for sure what the correct answer is. However, I'll just write down the entire infinitive phrases in these sentences, and you can see the answer based on that:
1. to see a great play
2. to cheer good plays
3. to practice until you know all the plays
A. Wasn't.. This is because if you seperatevthe contractioninto two words it is was not, this would make the sentence be "Wally was not capable of lifting the heavy box."
If you were to do the same thing with weren't it would sound like "wally were not capable of lifting the heavy box." This does not make sense because "wally" is singular (so is "was not") and "were not" is pleural.
Hope this helps
He was used to being made fun of.
We know this by him taking this reply in ‘with a sort of humble patience’. This means that he has experienced this kind of teasing - or even bullying before and he is used to it.
