Like we know that there are many steps which can be taken undo this problem.
Like we know that there are many steps when can be taken to undo this problem.
As we know that there are many steps which can be taken to undo this problem.
As we know that there are many steps where can be taken to undo this problem.
正如我们所知：As we know 题中后面是完整的句子，这里可以用that引导从句。 分析所给选项可知，steps后面是定语从句，从句中缺主语，故选which引导。 “来解决这个问题”是”采取步骤“的目的，所以用不定式表示。 解决问题：undo/solve this problem 故选C。
