老师说，当own表示“我们的”“是我们的”时，它只能与物主代词连用，不可以用于其他状况。但不是可以如此说吗？Own books must be taken care of by oneself.
没错，当own表示“我们的”“是我们的”时，它需要与物主代词（形容词性）。如：
I’d love to have my own room / a room of my own. 我喜欢有一个我们的房间。
We’ll have lunch in our own apartment. 大家将在我们的公寓里吃午饭。
Our cat has its own corner / a corner of its own in this room. 大家的小猫在这个房间里有它我们的一角。
因为名词所有格与物主代词性质相似，也 own 也可与物主代词连用。如：
They were Mr Smith’s own original curtains. 它们是史密斯先生自己原来的窗帘。
The name of the dead dog’s owner was on a disk on its collar. 这只死狗的主人的名字在狗颈圈的圆牌上。
你说的 Own books must be taken care of by oneself.不符合英语语法，可依据状况考虑改为：One must take care of his own books. / Your own books must be taken care of by yourself.
