B) link communications systems on various continentsª¤
C) the need to link communications systems on various is ever-increasingª¤
D) this need is now being met by the communications satellitesª¤

32.The maximum distance for high-frequency and straight line microwave tr
ansmission is ____ miles.ª¤
A) much more than 30ª¤
B) less than30ª¤
C) 30ª¤
D) about 30ª¤

33.The phrase ¡°marked a major step¡±(Line 1,Para. 5) most probably means____.ª¤
A) got significant stepª¤
B) was an important advanceª¤
C) made a progressª¤
D) marked in the history
ª¤
34.What is the author trying to tell us in the second paragraph?ª¤
A) Microwave radio relay.ª¤
B) Microwave itself.ª¤
C) Microwave¡¯s transmission.ª¤
D) Microwave¡¯s value.ª¤

35. In paragraph 6, ¡°...whose orbits are synchronous with the rotation of the earth so that this positions,...¡± means ____.ª¤
A) satellites are orbited in the same time with the rotation of the earthª¤
B) that moves as fast as the earth the earth turns roundª¤
C) that travels in the same direction with the earth turns roundª¤
D) that travels faster than the earth turns ª¤