28．the indian's chief purpose in writing the letter seems to ____ ?。?BR> a）politely refuse a friendly offer
b）describe indian customs
c）express their opinions on equal treatment
d）show their pride
29．different from the officials'view of education，the indians thought ____ ?。?BR> a）they taught different branches of science
b）they should teach the sons of the officials first
c）they had different goals of education
d）young women should also be educated
30．the tone of the letter as a whole is best described as ____ ?。?BR> a）pleasant b）polite c）inquiring d）angry
questions 31 to 36 are based on the following passage：
the focusing or sharpening of the image is performed by a special apparatus．in every camera，the farther the object is from the eye，the farther forward—and the nearer the object is to the eye，the farther backward—is its image thrown．in photographers'cameras，the back is made to slide，and can be drawn away from the lens when the object that casts the picture near， and pushed forward when it is far．the picture is thus kept always sharp．but no such change of length is possible in the eyeball，and the same result is reached in another way．the lens， namely，grows more convex（凸面的）when a near object is looked at，and flatter when the object recedes．this change is due to the antagonism of the“ciliary muscle（睫狀?。畉he ligament（韌帶），when the ciliary muscle is at rest，assumes such a spreadout shape as to keep the lens rather flat．but the lens is highly elastic；and it springs into the more convex form which is natural to it whenever the ciliary muscle，by contracting， makes the ligament relax its pressure．the contraction of the muscle，by thus tendering the lens more refractive，adapts the eye for near objects（“accommodatesit for them，as we say）：and its relaxation，by rendering the lens less refractive， adapts the eye for distant vision．a(chǎn)ccommodation for the near is thus the more active change，since it involves contraction of the ciliary muscle．when we look far off，we simply let our eyes go passive． we feel the difference in the effort when we compare the two sensation of change
b）describe indian customs
c）express their opinions on equal treatment
d）show their pride
29．different from the officials'view of education，the indians thought ____ ?。?BR> a）they taught different branches of science
b）they should teach the sons of the officials first
c）they had different goals of education
d）young women should also be educated
30．the tone of the letter as a whole is best described as ____ ?。?BR> a）pleasant b）polite c）inquiring d）angry
questions 31 to 36 are based on the following passage：
the focusing or sharpening of the image is performed by a special apparatus．in every camera，the farther the object is from the eye，the farther forward—and the nearer the object is to the eye，the farther backward—is its image thrown．in photographers'cameras，the back is made to slide，and can be drawn away from the lens when the object that casts the picture near， and pushed forward when it is far．the picture is thus kept always sharp．but no such change of length is possible in the eyeball，and the same result is reached in another way．the lens， namely，grows more convex（凸面的）when a near object is looked at，and flatter when the object recedes．this change is due to the antagonism of the“ciliary muscle（睫狀?。畉he ligament（韌帶），when the ciliary muscle is at rest，assumes such a spreadout shape as to keep the lens rather flat．but the lens is highly elastic；and it springs into the more convex form which is natural to it whenever the ciliary muscle，by contracting， makes the ligament relax its pressure．the contraction of the muscle，by thus tendering the lens more refractive，adapts the eye for near objects（“accommodatesit for them，as we say）：and its relaxation，by rendering the lens less refractive， adapts the eye for distant vision．a(chǎn)ccommodation for the near is thus the more active change，since it involves contraction of the ciliary muscle．when we look far off，we simply let our eyes go passive． we feel the difference in the effort when we compare the two sensation of change