Read the text below and answer the questions.

    Can lightning strike the same place twice? Let's figure out what makes it happen in the first place. 

    Lighting is electricity, and electricity involves tiny particles. Some particles have a positive charge and some have a negative charge. The two opposite charges pull towards each other like the north and south ends of magnets. 

   Usually electric charges are fairly balanced but the turbulent winds of a storm caused electric charges to separates within the cloud. 

    Most lightning occurs within the cloud itself, but were concerned about the lightning between clouds and the ground. 

   Lightning starts with negative charges moving from the clouds towards the ground. Scientists call it a stepped leader. Meanwhile an upward leader forms as positive charges move up from the ground usually from tall objects when a stepped leader and an upward leader meet, it makes a path for a much larger and brighter electric current to shoot up into the cloud. This is what we see in the sky as lightning. It happened so quickly that lightning seems to travel from the cloud to the ground.

    When in fact the opposite is true. So, can lightning strike the same place twice?Absolutely. For example Toronto CN Tower is struck by lightning around seventy five times each year. In fact in August 2011 the tower was shocked a record-breaking 52 times in 84 minutes. But don't worry the tower was built to withstand it. So its a safe place to be if lightning strikes once twice or even 52 times. 

Source: Toronto Symphony Orchestrahttps://you.tube/Cz_uYBx1G5s

What is stepped leader on the text above?