Should flag questions lacking a question mark.

[hippietrail]

The Error

Examples:

1. Do you often see questions like this.
2. Can they be fixed
3. Why does it happen!
4. Am I the only one who is annoyed.

Potential Edge Cases
Detecting questions is not as straightforward as you might think when the ? is missing.
They mostly start a present of past form of "be" or "do", a modal verb such as "can" or "should", or an interrogative word such as "what" or "how". In all the verb cases, the negative contractions are also possible.

But this isn't enough on its own. Many statements also fit this pattern.

Maybe the interrogatives have to precede one of those types of verbs, and maybe a pronoun in subject form has to follow said verb?

Implementation
It might be easier to implement if there were a version of ExprLinter that worked on sentences rather than "chunks".