A．meaning shift
B．loss of meaning
C．widening of meaning
D．narrowing of meaning

A．16th
B．17th
C．18th
D．19th

A．Disappearance.
B．Untouchable.
C．Desirablity.
D．Physician.

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.

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

A．many industrialists feel no concern for the improvement of pollution control
B．breathing low concentrations of urban dust does not necessarily sicken or kill people
C．no acceptable biological mechanism has been suggested to explain the toxicity of low concentration of urban dust
D．scientists have done nothing to reveal the mystery of the toxicity of low concentration of urban dust

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

A．Objective.
B．Mechanical.
C．Superficial.
D．Paradoxical.

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.

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