31．in order to focus on distant objects，the lens of the eye ____ ?。?BR> a）becomes more convex b）becomes more active
c）becomes more refractive d）flattens
32．the ligament，when not acted on by the contraction of the ciliary muscle，____?。?BR> a）maintains its pressure on the lens so that the lens remains flat
b）relaxes its pressure on the lens so that it remains convex
c）maintains its pressure on the lens so that the lens remains convex
d）relaxes its pressure on the lens so that it remains flat
33．functionally，we may compare ____ ?。?BR> a）the lens of the camera with the lens of the eye
b）the lens of the camera with the ciliary muscle
c）the lens of the eye with the sliding of the back of the camera
d）the sliding of the back of the camera with the adaptability of the eyeball
34．which of the following activities is most tiring for the lens of the eye？
a）looking at a distant mountain．
b）being a“sidewalk superintendent．
c）watching squirrels being fed．
d）reading a book．
35．the tone of this passage can best be described as ____ ．
a）professionally scientific b）argumentative
c）matter of fact and formal d）informal and matter of fact
questions 36 to 40 are based on the following passage：
are you aware that you actually possess six senses？the sixth is a muscular sense responsible for directing your muscles intelligently to the exact extent necessary for each action you perform．for example，when you reach for an object，the sensory nerves linking the muscles to the brain stop your hand at the correct spot．this automatic perception of the position of your muscles in relation to the object is your muscular sense in action．
muscles are stringy bundles of fibers varying from one five thousandth of an inch to about three inches．they have three unique characteristics： they can become shorter and thicker；they can stretch；and they can retract to their original po- sition．under a high-powered microscope，muscle tissue is seen as long，slender cells with a grainy texture like wood．
more than half of a person's body is composed of muscle fibers，most of which are involuntary，in other words，work without conscious direction．the voluntary muscles，those that we move consciously to perform particular actions，number more than five hundred．women have only 60 to 70 percent as much muscle as men for their body mass．that is why an average woman can't lift as much，throw as far，or hit as hard as an average man．
c）becomes more refractive d）flattens
32．the ligament，when not acted on by the contraction of the ciliary muscle，____?。?BR> a）maintains its pressure on the lens so that the lens remains flat
b）relaxes its pressure on the lens so that it remains convex
c）maintains its pressure on the lens so that the lens remains convex
d）relaxes its pressure on the lens so that it remains flat
33．functionally，we may compare ____ ?。?BR> a）the lens of the camera with the lens of the eye
b）the lens of the camera with the ciliary muscle
c）the lens of the eye with the sliding of the back of the camera
d）the sliding of the back of the camera with the adaptability of the eyeball
34．which of the following activities is most tiring for the lens of the eye？
a）looking at a distant mountain．
b）being a“sidewalk superintendent．
c）watching squirrels being fed．
d）reading a book．
35．the tone of this passage can best be described as ____ ．
a）professionally scientific b）argumentative
c）matter of fact and formal d）informal and matter of fact
questions 36 to 40 are based on the following passage：
are you aware that you actually possess six senses？the sixth is a muscular sense responsible for directing your muscles intelligently to the exact extent necessary for each action you perform．for example，when you reach for an object，the sensory nerves linking the muscles to the brain stop your hand at the correct spot．this automatic perception of the position of your muscles in relation to the object is your muscular sense in action．
muscles are stringy bundles of fibers varying from one five thousandth of an inch to about three inches．they have three unique characteristics： they can become shorter and thicker；they can stretch；and they can retract to their original po- sition．under a high-powered microscope，muscle tissue is seen as long，slender cells with a grainy texture like wood．
more than half of a person's body is composed of muscle fibers，most of which are involuntary，in other words，work without conscious direction．the voluntary muscles，those that we move consciously to perform particular actions，number more than five hundred．women have only 60 to 70 percent as much muscle as men for their body mass．that is why an average woman can't lift as much，throw as far，or hit as hard as an average man．