In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.
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Question: The atomic radius of a chemical element is a measure of the size of its atoms , usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding shells of electrons .

Answer: The atomic radius of an element is the distance between the nucleus and the edge of the electron cloud .

Question: France has a close association with the Modern Olympic Games ; it was a French aristocrat , Baron Pierre de Coubertin , who suggested the Games ' revival , at the end of the 19th century .

Answer: At the end of the 19th century , the Baron Pierre de Coubertin suggested having the Olympic Games again .

Question: The Roman Kingdom , also referred to as the Roman monarchy , or the regal period of ancient Rome , was the earliest period of Roman history , when the city and its territory were ruled by kings .

Answer:
The Roman Kingdom was the monarchical government of the city of Rome and its territories .