The word “microbes” in paragraph 3 could best be replaced by which of the following?

The phrase "held back” in paragraph 1 means________

The word "pigment" at the end of the first paragraph means________.

The researcher mentioned in the passage are concerned about unwanted noise because it can_________.

The word ‘monumental’ in Paragraph 2 means __________.

Hummingbirds are small, often brightly colored birds of the family Trochilidae that live exclusively in the Americas. About 12 species are found in North America, but only the ruby-throated hummingbird breeds in eastern North America and is found from Nova Scotia to Florida. The greatest variety and number of species are found in South America. Another hummingbird species is found from southeastern Alaska to northern California. Many hummingbirds are minute. But even the giant hummingbird found in western South America, which is the largest known hummingbird, is only about 8 inches long and weighs about two-thirds of an ounce. The smallest species, the bee hummingbird of Cuba and the Isle of Pines, measures slightly more than 5.5 centimeters and weighs about two grams. Hummingbirds' bodies are compact, with strong muscles. They have wings shaped like blades. Unlike the wings of other birds, hummingbird wings connect to the body only at the shoulder joint, which allows them to fly not only forward but also straight up and down, sideways, and backward. Because of their unusual wings hummingbirds can also hover in front of flowers so they can suck nectar and find insects. The humming- bird's bill, adapted for securing nectar from certain types of flowers, is usually rather long and always slender, and it is curved slightly downward in many species. The hummingbird’s body feathers are sparse and more like scales than feathers. The unique character of the feathers produces brilliant and iridescent colors, resulting from the refraction of light by the feathers. Pigmentation of other feathers also contributes to the unique color and look. Male and female hummingbirds look alike in some species but different in most species; males of most species are extremely colorful. The rate at which a hummingbird beats its wings does not vary, regardless of whether it is flying forward, flying in another direction, or merely hovering. But the rate does vary with the size of the bird - the larger the bird, the lower the rate, ranging from 80 beats per second for the smallest species to 10 times per second for larger species. Researchers have not yet been able to record the speed of the wings of the bee humming-bird but imagine that they beat even faster. Most hummingbirds, especially the smaller species, emit scratchy, twittering, or squeaky sounds. The wings, and sometimes the tail feathers, often produce humming, hissing, or popping sounds, which apparently function much as do the songs of other birds. 

According to the passage, where are hummingbirds found?

The word "appealing" is closest in meaning to ........

All of the following are defined in the passage EXCEPT ............

Mickey Mantle was one of the greatest baseball players of all time. He played for the New York Yankees in their years of glory. From the time Mantle began to play professionally in 1951 to his last year in 1968, baseball was the most popular game in the United States. For many people, Mantle symbolized the hope, prosperity, and confidence of America at that time. Mantle was a fast and powerful player, a “switch-hitter” who could bat both right-handed and lefthanded. He won game after game, one World Series championship after another, for his team. He was a wonderful athlete, but this alone cannot explain America’s fascination with him. Perhaps it was because he was a handsome, red-haired country boy, the son of a poor miner from Oklahoma. His career, from the lead mines of the West to the heights of success and fame, was a fairy-tale version of the American dream. Or perhaps it was because America always loves a “natural”: a person who wins without seeming to try, whose talent appears to come from an inner grace. That was Mickey Mantle. But like many celebrities, Mickey Mantle had a private life that was full of problems. He played without complaint despite constant pain from injuries. He lived to fulfill his father’s dreams and drank to forget his father’s early death. It was a terrible addiction that finally destroyed his body. It gave him cirrhosis of the liver and accelerated the advance of liver cancer. Even when Mickey Mantle had turned away from his old life and warned young people not to follow his example, the destructive process could not be stopped. Despite a liver transplant operation that had all those who loved and admired him hoping for a recovery, Mickey Mantle died of cancer at the age of 63. 

What is the main idea of the passage?

What causes dodder to grow in a particular direction?

"It” in the passage refers to_______.