这个理论虽然有趣，但存在严重缺陷。

The theory, while interesting, is deeply ___flawed.

这个计划从一开始从根本上就有缺陷。

The plan was fundamentally ___flawed from the very beginning.

尽管初衷是好的，但整体方法仍有缺陷。

Despite some good intentions, the overall method remains ___flawed.