没法子

méi fǎ zi le wǒ men bì xū jiào jǐng chá le

没法子了，我们必须叫警察了。

There's no help for it. We shall have to call the police.

tā men méi fǎ zi zhèng míng tā yǒu zuì

他们没法子证明他有罪。

They can't prove him guilty.