[简答题]Section B
Directions: In the following passage, a number of words are missing. Fill in each blank with a single suitable word.

The world is filled with many interesting sounds. Some are unpleasant to our ears while others are very (46) to hear, in a single day you probably hear hundreds of different (47) . All sounds are different. Some may be soft; others may be (48) . Some sounds are high; others are low. Some sounds are useful. Without sound we cannot talk or listen to (49) another. The ringing of the alarm clock (50) people up. The hooting of a car warns people (51) danger.
Some sounds are harmful when planes fly low over the land. The very loud sounds can cause (52) to houses. Very loud sound can even make people (53) .
We know sound travels about one kilometre in three seconds. In a (54) you see the lightning first and then hear the thunder. This is because