Caffeine is a natural ingredient in coffee, cocoa, tea, and chocolate, and is added to some prescription and non-prescription drugs. Despite being "natural," caffeine is also a powerful drug which greatly affects the body. In healthy, rested people, a dose of 100 milligrams (about one cup of coffee) increases alertness, banishes drowsiness, quickens reaction time, it enhances intellectual and muscular effort, and increases heart and respiratory rates. Drinking one to two cups of coffee an hour before exercise encourages the body to preserve glycogen and burn fat -----something that results in greater endurance. In addition, caffeine masks fatigue. In doses above 300 milligrams, caffeine can produce sleeplessness, nervousness, irritability, headaches, heart palpitations, and muscle twitches. Caffeine is also habit-forming, and those who try to suddenly stop after heavy use may experience such withdrawal symptoms as headaches, lethargy, irritability, and difficulty in concentrating.

The main idea of this passage is that caffeine

Select the best version of the underlined part of the sentence.

Many companies are now using social networking sites like Facebook and MySpace to market there service and product.

Select the best version of the underlined part of the sentence.

A key factor taken into account during city planning is where major services and amenities will be located.

Select the best version of the underlined part of the sentence.

The bizarre creatures known by electric eels are capable of emitting an incredible 600 volts of electricity.

Before clocks were made, people kept track of time by other means. In ancient Egypt, people used a water clock. Water dripped slowly from one clay pot into another. People measured time according to how long it took one pot to empty and the other one to fill. Candle clocks were common during the Middle Ages. As such, when a candle burned, marks on its side showed about how much time had passed. A final ancient way to measure time was the sundial, which used the movement of the sun across the sky. The shadows moving across the face of the sundial showed the current time.

What is the main idea?

The main idea of the passage is that television

Guillermo Gonzalez Camarena became a successful inventor at an early age. By the age of seven, he had constructed a variety of electronically-propelled toys to play with; he later designed and built his own amateur radio and a functioning telescope. In 1940, when he was only 23, Camarena obtained the world's first patent for color television. Camarena's early color television transmission system was the first one to be approved by the U.S. Federal Communications Commission. Other color-television technologies came after Camarena's patented invention, but his system is still used by a number of scientists today. In sentence 2 (the one that is underlined), the word "functioning" most nearly means:

Katelyn was __________ when she learned the EPLA Valentines Dance was cancelled; she had looked forward to it all week. 

Today, more than 200 species of fish ***(lives OR live)*** in the 18,000-acre marine park