He was not unintelligent, but he was lazy.

他并非不聪明，不过就是懒。

Being dyslexic does not mean that one is unintelligent. Far from it.

诵读困难并不意味着人不聪明。绝非如此。

He certainly was not unintelligent.

他绝对不傻。

He believes him to be a weak and unintelligent man.

他相信自己是一个软弱的傻子。

It appears to be unintelligent behavior.

这似乎是愚昧的行为。