In Present tenses^x, Articles^x, Gerunds^x

Just to clarify about the indefinite article: it's OK to say "stores and restaurants see sharp decline in sales" without the article when using the present tense; in fact it has the ring of a newspaper headline. On the other hand when using the gerund not using the article in this...

English grammar seems to be full of exceptions more than rules. This is a vast topic that could easily fill a book (or two). Where would you like to start? Plurals, past tense, present tense, gerunds, infintives, articles...