The world      many interesting sounds. Some are unpleasant to our ears while      are very pleasant to hear. In a single day you probably hear      sounds. All sounds are different. Some      loud, some sounds are high, others are low, some sounds are useful.
     sound we can’t talk or listen to each other. The ringing of the alarm clock wakes people up. The hooting(鸣笛声) of a car warns people of danger.
Some sounds are harmful. When planes fly low on the land, the very loud sounds can damage the house. Very loud sound can even make people      .We know sound travels about one kilometer in three            . In a thunder storm you see the lighting first and then hear the thunder. This is because light travels          than sound.
Next time you see lighting, count the number of seconds before you hear      . Divide this number by three. This will tell you     kilometers away the thunder storm is.

A．full of B．fill with C．is filled of D．is filled with

A．others B．the other C．another D．the others

A．hundreds of B．few C．much D．one hundred of

A．may B．maybe C．may be D．can

A．Of B．With C．Without D．By

A．happy B．blind C．deaf D．off

A．hours B．days C．minutes D．seconds

A．more B．faster C．quickly D．enough

A．the thunder B．the noise C．the sound D．the next

A．how much B．how many C．how far D．how long