Easy situation puzzles

Sherlock Holmes had a secret room, and the key to it was in a chest of drawers. He didn’t let anyone in there – neither Dr. Watson, nor Mrs. Hudson. But when Sherlock Holmes and Dr. Watson left, Mrs. Hudson decided to see what was in the room, took the key, opened the room, and entered. She walked around the room, approached a table, opened a book lying on it. Suddenly, she heard footsteps downstairs, and Holmes’s voice, “I forgot something.” Mrs. Hudson quickly closed the book, put it back, went to the door, turned off the light, left the room, closed the door, and managed to put the key back. Holmes took the key, opened the door, looked into the room, and immediately asked, “Mrs. Hudson, why did you enter my room?” How did Holmes know that Mrs. Hudson had entered his room?

A man looked out of the window and soon died. What happened?

In the 1940s, a real football game in Brazil ended with an unusual score of 0.5 - 0. What happened?

Alexander shot at the king, but no one condemned him. Why?