Как правильно расскрыть скобки? mark (not talk) on the phone when his boss (enter) the room. he (tidy) up his desk

i saw an elephant for the first time in a zoo, when i was 4. this animal is very big, elephants live in india. people there use the elephants for transportation of trees and other heavy things. i like this animal because it is clever. i wish everyone could see this amazing animal, one must go and see it.