A: Than you for lending me the book.
B: Sure. But it's very difficult one, you need to have a dictionary at your elbow.
A: But I'm not used to looking up every new word when I'm reading a novel. I only look up the most necessary ones.
at one's elbow
At one's elbow的意思是：在手边，在身边，很近。
E.g. Her mother was always at her elbow to help her.
E.g. Mr. Chalfont felt scandal at his elbow.
E.g. The president's wife was always at his elbow whenever an important decision had to be taken.
E.g. She stayed up all night writing the paper with a pot of coffee at her elbow.
be used to：习惯于做.....
E.g. She isn't used to living in the countryside now.
look up a word：查字典
E.g. Go and get a dictionary and we'll look the word up.
E.g. The primary meaning of the word isn't used now, but you can look it up in a big dictionary.
E.g. When you do not understand a word, you can look it up in this dictionary.
E.g. How am I supposed to look up a word I don't know how to spell?