They could ascertain the extent of the damage.他们可以查实破坏程度。

We're unable to ascertain who the owners are.我们无法确定所有者是谁。

Ascertain which services your bank is providing.弄清楚你的银行提供什么样的服务。

They had ascertained that he was not a spy.他们已经确定他不是间谍。