A lot of families in Britain grow vegetables． A few people grow unusual or strange vegetables． But a great many people grow tomatoes． My neighbor grows the biggest， sweetest， happiest tomatoes in the world． "How do you do it？" I ask． "Why can't I grow tomatoes like yours？"

"I talk to them，" my neighbor says． "I've been talking to my tomatoes for years．" Up to now， I have always laughed at this．

This summer， some scientists carried out an interesting experiment， and I have just read their report．

Three sets of tomato plants were grown． Nobody talked to the first set， but every day for a month， a recording of a man's voice was played to the second set， and a recording of a woman's voice was played to the third set． At the end of the month， the second set of plants had grown four centimeters taller than the first， and the third set of plants had grown five centimeters taller than the second． The plants liked the woman's voice best．

"We can't explain it，" a scientist said， "But sound waves surely help the tomatoes to grow． Plant growers have always paid attention to light and water． Now we advise you to think of sound waves in the same way．"

31． The writer's neighbor grows better tomatoes because he 　　．

A． stays with them

B． laughs at them

C． talks to them

D． thinks of them

32． Through the experiment， the scientists proved that 　　 helps tomatoes to grow best．

A． a man's voice

B． a woman's voice

C． the sound of nature

D． the sound of animals

33． By the underlined sentence the scientist means 　　．

A． plants don't grow without sound waves

B． scientists have found the secret of sound waves

C． sound waves are more important than light and water

D． plant growers should also play attention to sound waves