Here is another one. 'She opened the old book. A pressed flower fell out.'
One example could be: 'The sun was setting. A lonely traveler walked the old road. He heard a strange noise. It was just the wind in the trees.'
One could be 'The door creaked open. A shadowy figure with no face stared at me.'
I woke up to find a handprint on my window. It was on the inside.
Sure. Story 1: She found a key. It opened a hidden door. A world of magic awaited. Story 2: He lost his hat. In the search, he met a friend. They shared a great adventure. Story 3: The cat chased a mouse. The mouse hid in a hole. The cat sat and waited patiently.
Sure. 'The old house was silent. Then I heard a child's laughter from the attic.'
One more example could be 'When the lights came on, the real culprit was the one person no one suspected - the cat, whose paw prints led to the hidden evidence.' This ending is a bit more light - hearted but still fits the mystery genre. It plays with the idea of an unexpected culprit, which is a common trope in mystery stories. It also gives a touch of humor with the cat being the culprit, while still providing a logical explanation through the paw prints leading to the evidence.
One could be: 'I woke up to a noise. It was coming from inside the closet.'
One could be 'I heard a strange noise in the attic. When I went to check, a cold hand grabbed my arm.'
One: 'She waited at the station every day. He never came back.'
One example could be 'The last man on Earth sat alone in a room. There was a knock on the door.' It creates horror through the sudden and unexpected event in a seemingly desolate situation.