The Beginning of Change 3. There was always an important piece missing for his inventions. He needed batteries to power his homemade devices. Kelvin did not have the benefit of science education at school. Yet, he figured out how to make a battery using soda, metal, and tape. These are ingredients he found at a neighborhood dump! With this battery, the possibilities for his inventions were endless.

Read the third paragraph of the article and answer the following question.
What is the best sentence to show an implicit detail in this paragraph?

a
Kelvin did not take science classes at school.

b
Kelvin was very intelligent and figured out quite a bit about science.

c
Kelvin found the ingredients for the battery at the local landfill.

d
With the battery Kelvin made, the possibilities were endless.

(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.”)

The greatest gift the sumerians gave the world was the invention of writing. the sumerians were a wealthy people. they needed some way to keep track of what they owned. they began drawing pictures. they used a reed as a pen. they drew on soft pieces of clay. the soft clay was then dried in the sun. the tablet became a permanent record. later, the sumerian drawings changed into wedge-shaped symbols. this kind of writing is called cuneiform. by putting symbols together, the sumerians could write entire sentences.

Which phrase from the article suggests a tone that is formal but subjective? a- "thirty-six inches long and sixteen inches wide" b- "loads of fun with it" c- "most generous and attractive" d- "must be new subscribers"