It is wrong to differentiate between pupils according to their family background.
It is wrong to differentiate between students according to their family background.
It's wrong to differentiate between boys and girls.
It is wrong differentiate between pupils according to their family background.
It need to think it over well yourself, carefully differentiate, then decide what course to follow.
它需要自己好好掂量、掂量 、 仔细辨别, 然后决定何去何从.