(误)So as to be in time we hurried.
(正)In order to be in time we hurried.(so as to只可放在句中，in order to可放在句首或句中。)
(误)It's very foolish for you to say so.
(正)It's very foolish of you to say so.(表示评价的形容词被带逻辑主语的不定式修饰时，介词要用of.)
(误)Didn't you ask them to never do that?
(正)Didn't you ask them never to do that?(never要放在to之前。)
(误)Here is a new book for you to read it.
(正)Here is a new book for you to read.(作形容词用法的带逻辑主语的不定式for you to read的宾语，实际上就是它所修饰的new book，其后不可再加宾语。)
(误)He is old enough so that he can go to school.
(正)He is old enough to go to school.(形容词+enough+不定式表示足够…而可。)
(误)He was so good to send me a lot of books.
(正)He was so good as to send me a lot of books.(so……as to表示如此…以致。)
(误)You had better not to go out in the rain.
(正)You had better not go out in the rain.(had better(not)后接原形不定式。)
(误)Do you like listening to others to talk?
(正)Do you like listening to others talk?(感官动词或使役动词的宾语补语用原形不定式。)