通常是用doing,因为turn后面的to是一个介词,后面应该接ing形式。你们老师说接do是错误的。turn后可以直接接to sb,表示向某人求助。类似的词语有listen to 后面要接动词的时候一定是ing形式。
turn to后面只能加名词和动名词(也就是doing形式)没见过加原型的,你们老师说加do的那个句子是什么能不能写出来看一下?
接动词的情况,turn to作"变成","转向(原来在做另外一件事)"讲,例如:
He is turning to be strong.他正在变强壮。
He turned to keep silent when he saw me.他看到我就安静了下来。
1. turn to doing sth 开始从事/致力于...
如: The farmers here turned to keeping cattle from 2012.
2. turn to sb/sth 求助于,转向
如:He turned to me for help.
Please turn to Page 911.