Air is all around us. It is around us when we walk and play. From the moment we are born, air surrounds us. When we sit down, it is around us. When we go to bed, air is also around us. No matter where we are on earth, air surrounds us. We live in air.All living things need air. Living things cannot live without air. We can go without food or water for a few days, but we cannot live for more than a few minutes without air. When we are working or running, we need more air. So we breathe faster than usual. When we are asleep, we need less air.
People can live without food or water for______.
A．a few months
B．a few weeks
C．a few days

The word primarily in the passage is closest in meaning to
A．mostly
B．somewhat
C．finally
D．always

According to paragraph 7, why has the underclass emerged？
A．The new term was necessary because the lower class enjoyed a higher lifestyle. than it had previously.
B．The increase in crime has supported a new class of people who live by engaging in illegal activities.
C．Changes in the economy have caused an entire class of people to survive by welfare or crime.
D．Minimum-wage jobs no longer support a class of people at a standard level in the economic system.

Listen again to part of the lecture. Then answer the question. Why does the professor say this: G
A．To compare different ways of conveying a message
B．To explain an important theory of communications
C．To show that miscommunication is a serious problem
D．To introduce a controversial topic of conversation

Look at the four squares [■] that show where the following sentence could be inserted in the passage. The working poor constitute a large portion of those who are poor. Where could the sentence best be added？ Click on a square [■] to insert the sentence in the passage.
A．Square Ａ.
B．Square Ｂ.
C．Square Ｃ.
D．Square Ｄ.

Which of the following are examples of the marketing function of harvesting？ Click on two answers.
A．picking cotton
B．Sorting eggs by size
C．Moving corn to a grain elevator
D．Milking cows