Formal/Philosophical:
* The argument is flawed, ergo, the conclusion is invalid. (This means the argument is flawed, therefore the conclusion is invalid.)
* The evidence points to a clear motive, ergo, the suspect must be considered guilty. (The evidence shows a clear motive, therefore the suspect must be considered guilty.)
Informal:
* The traffic was terrible, ergo, I was late for work. (The traffic was terrible, therefore I was late for work.)
* I forgot my wallet, ergo, I couldn't buy lunch. (I forgot my wallet, therefore I couldn't buy lunch.)
Humorous:
* The cake was delicious, ergo, I ate the whole thing. (The cake was delicious, therefore I ate the whole thing.)
* It was raining, ergo, I stayed inside and watched movies. (It was raining, therefore I stayed inside and watched movies.)
Note: While "ergo" is a perfectly valid word, it's often considered more formal or academic. It's not as common in everyday speech, but it can be used in writing or speaking to add a bit of formality or emphasize a logical connection.