Never use the imperative, and it is also never proper to construct a sentence using mixed moods. I don't understand a thing I say. This sentence every third, but it still comprehensible. This would easier understand fewer had omitted. This impossible except context.
All invalid syllogisms break at least one rule.
This syllogism breaks at least one rule. Therefore, this syllogism is invalid. Nostalgia ain't what it used to be. They don't write oldies like they used to. I used to think I was indecisive, but now I'm not so sure.