The speaker replaces peoples' words because
a) he wants them to use better words.
b)he feels that words are unimportanti
c)he does not believe what people say.
d)he wants to show off his intelligence,

If your job was precarious,would you look for a new one? explain.

(1) fire extended humans’ geographical boundaries by allowing them to travel into regions that were previously too cold to explore. (2) it also kept predators away, allowing early humans to sleep securely. (3) fire, in fact, has been a significant factor in human development and progress in many ways. (4) other obvious benefits of fire are its uses in cooking and in hunting. (5) probably even more important, however, is that learning to control fire allowed people to change the very rhythm of their lives. (6) before fire, the human daily cycle coincided with the rising and setting of the sun. (7) with fire, though, humans gained time to think and talk about the day’s events and to prepare strategies for coping with tomorrow. the sentence that expresses the main idea is: (type the number of the sentence. then click “go.”)

Read the excerpt from it's our world, too! : young people who are making a difference.the author’s purpose in this excerpt is to