Verbs show action and tense indicates time. The present tense shows ongoing or habitual actions while past tense shows completed actions. The present continuous (e.g., "are playing") expresses temporary or ongoing actions happening now. The simple present expresses facts, schedules or repeated/habitual present actions (e.g., "works"). The past continuous ("were watching") describes an action that was ongoing at a specific time in the past. Time expressions like "at 3 o'clock" are used with the past continuous to situate the action in time.