indifferent

We didn't like the restaurant much - the food was indifferent and the service rather slow.

我们不怎么喜欢这家餐馆——饭菜一般，上菜也相当慢。

He found it very hard teaching a class full of indifferent teenagers.

他发觉教一班无动于衷的十几岁的孩子真是头疼。