a)boil down to something informal if a long statement, argument etc boils down to a single statement, that statement is the main point or cause 要点是,归结为
It boils down to a question of priorities.
归根到底是事情轻重缓急的问题。
b)boil something ↔ downREDUCE to make a list or piece of writing shorter by not including anything that is not necessary 压缩,简化〔清单或文章〕
You can boil this down so that there are just two main categories.
你可以把这个压缩到只有两大类。
c)DFCif a food or liquid boils down, or if you boil it down, it becomes less after it is cooked 煮稠,浓缩,缩掉