Feeling tense because you don't know whether to use the present simple or the present perfect continuous? Try our review of the tenses — the most important ways of expressing the past, present and future in English.
Samuel L. Jackson doesn't just talk tough in the movies. Lately, he's been getting tough on bad grammar, too — whether it's used by fans of his on Twitter or even by Barack Obama. "Somebody needs to be the grammar police," the 64-year-old actor says.