cannot but

1. 不得不

One cannot but admire her even if one may not like her.

你即使不喜欢她也只得佩服她。

He cannot but give it up.

他不得不放弃它。

2. 不能不

One cannot but be moved by his acting.

人们不能不被他的表演所感动。

cannot ... too ...

1. 越……越好

You cannot be too careful in examinations.

考试时越仔细越好。