1. PAST TENSE SIMPLE
+ She watched a film yesterday.
- She didn't watch a film yesterday.
? Did she watch a film yesterday?
2. PAST TENSE CONTINUOUS
+ She was watching a film yesterday at 3 o'clock.
- She wasn't watching a film yesterday at 3 o'clock.
? Was she watching a film yesterday at 3 o'clock?
3. PAST PERFECT SIMPLE
+ She had watched a film before we met.
- She hadn't watched a film before we met.
? Had she watched a film before we met?
4. PAST PERFECT CONTINUOUS
+ She had been watching a film for an hour before we met.
- She hadn't been watching a film for an hour before we met.
? Had she been watching a film for an hour before we met?