不幸的是，到目前为止，还没有一种简单的方法可以让我们知道水什么时候将被完全净化。

Unfortunately, until now, there was no simple way of knowing when the water was purified.

youdao

不幸的是，到目前为止，还没有一种简单的方法可以让我们知道水什么时候将被完全净化。

Unfortunately, until now, there was no simple way of knowing when the water was purified.

youdao