① into是介词； 而in to是副词in＋介词 to； 因此into是表示动作或运动的方向,朝向是某个地方的内部； 而in to理论上没有关联,只是根据in前面的动词或to后面的名词来判断使用或出现的条件.比如：He turned his paper in to his teacher.这里的in与其说是和to一起用,不如说是turn ...in的延续.
② 判断使用的一个关键：设想into回答的是where（目的）的问句； 而in to则是否能替代为in order to.比如：
I am afraid to go into that place.---> Where?into that place.不能是in to；
He came in to get his money.---> He came in,in order to get his money.不是into.
③ into还有“变成”,“接触”甚至“感兴趣”的意思； 对应的可替换的词是“result of change”和“against”以及“interested”
He changed into a monster.-- result of change
He drove into a tree.-- against
He is really into this book.-- interested
