单项选择题

A．Airborne dust may trigger suppressor macrophage suici……

Which of the following statements about human alveolar macrophage is TRUE

A．Airborne dust may trigger suppressor macrophage suicides.
B．Airborne dust may trigger stimulatory macrophage suicides.
C．The ratio of suppressor macrophages to stimulatory ones in people with lung diseases is much higher than that in people with healthy lungs.
D．Only stimulatory macrophages show responses to airborne dust.

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单项选择题This passage is mainly about _____.

A．how inhaled dust harms the lungs
B．the function of Environmental Protection Agency
C．the function of human alveolar macrophages
D．studies by Environmental Protection Agency

单项选择题According to this passage, Environmental Protection Agency _____.

A．is the only agency studying the effects of air pollution on health
B．has launched a surprised attack on researchers
C．has decided to decrease the permitted concentration of airborne dust
D．has tremendously improved pollution control

单项选择题How did the nineteenth-century defenders of photography stress the photography

A．They stressed photography was a means of making people happy.
B．It was art for recording the world.
C．It was a device for observing the world impartially.
D．It was an art comparable to painting.

单项选择题Why does the author introduce Abstract Expressionist painter

A．He wants to provide an example of artists who, like serious contemporary photographers, disavowed traditionally accepted aims of modem art.
B．Be wants to set forth an analogy between the Abstract Expressionist painters and classical Modernist painters.
C．He wants to provide a contrast to Pop artist and others.
D．He wants to provide an explanation of why serious photography, like other contemporary visual forms, is not an should not pretend to be an art.

单项选择题The author is concerned with _____.

A．defining the Modernist attitude toward art
B．explaining how photography emerged as a fine art
C．explaining the attitude of serious contemporary photographers toward photography as art and placing those attitudes in their historical context
D．defining the various approaches that serious contemporary photographers take toward their art and assessing the value of each of those approaches