The problem with 2 aqnd 3 is that you had a "that clause" construction, which made it sound awkward. # 1 is somewhat understood but not idiomatically smooth, nor it waas clear. I would word it this way: Tom found it hard to come up to Bob with mathematic questions.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
seagullCan we rewrite #1 for #2 or #3?No. Simply because the structure is 'hard to do'.
seagulls it possible to make a sentence that means the same as #1 by using the "(Tom) found it hard that ..." construction?I don't think so. The best I can do: Tom found it hard coming up to Bob in mathematics.
grammarfreakwith mathematics questions.I don't think that is what is meant: they are not writing questions.
seagullThe difference between #1 and #2&3 comes from the fact that 'to come to Bob' is a 'target' while 'that he comes/came up to Bob' is a 'fact.' Can we understand that way?Actually, I had thought about that for a moment, but I don't think that is the problem: the problem is in the particular semantics. If he succeeds in 'coming up' (as he does in #2 and #3
seagullIsn't it possible to consider that 'to infinitives' represent 'the idea that if someone is to do something?Yes, infinitives in general represent the potential, the not-yet-realized, and that is handy to remember, though it reveals itself in many different forms and sometimes is only a marginal aspect of what is being said.