We use the Present Perfect to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc. We CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc. Examples: I have seen that movie twenty times. I think I have met him once before. There have been many earthquakes in California. People have traveled to the Moon.
The warm water warms the air above it. It starts as a low pressure area then circling winds pick up the energy from the warm air. Eventually it creates the hurricane.
On Saturday's, I wake up and go to the restroom. Then I ask my mom what chores need to be done so I can do my chores. After my chores I do my homework, and when I'm done I enjoy the rest of the day off.
The author's main purpose of writing memoir Night was to describe the terrible conditions of war.
Explanation: The author has described about the inhumanity to nature when the war has took place. The crying night souls of the people are expressed in the poem where they starve for happiness and peace.