很长时间我们都无法解释这一奥秘，但是我想我们最后掌握线索了。

For long we have been unable to find an explanation of the mystery, but at last I think we are on the track of it.

youdao

很长时间我们都无法解释这一奥秘，但是我想我们最后掌握线索了。

For long we have been unable to find an explanation of the mystery, but at last I think we are on the track of it.

youdao