III-Add commas where necessary. 1- We enjoyed the city where we spent our vacation. 2- We enjoyed Mexico City where we spent our vacation. 3- One of the elephants which we saw at the zoo had only one tuck. 4- In Venezuela, there are plants which can eat insects with their roots. 5- One of the most useful materials in the world is glass which is made chiefly from sand, soda, and lime. 6- A rebel is a person who resists or fights against authority. 7- Petroleum which some people refer to as black gold is one of the most valuable resources in the world today. 8- You don’t need to take heavy clothes when you go to Bangkok which has one of the highest average temperatures of any city in the world. 9- A political party is a group of people who control or seek to control government. 10- We had to use a telephone, so we went to the nearest house. The woman who answered our knock listened cautiously to our request. 11- According to the article which I read, the police arrested the man who had robbed the First National Park. The man who was wearing a plaid shirt and blue jeans was caught shortly after he had left the bank. 12- Glaciers which are huge masses of ice that flow slowly over land form in the cold Polar Regions and in high mountains.