他的解释中没有一丝真相。

There isn't a ___grain of truth in his explanation.

她的论点包含一丝智慧，但大部分是有缺陷的。

Her argument contains a ___grain of wisdom, but it's mostly flawed.

即使在他的道歉中，也没有一丝诚意。

Even in his apology, there was not a ___grain of sincerity.