题目内容：

    According to a study published in the pre-print website bioRxiv, a team of Israeli scientists recorded tomato and tobacco plants producing sound frequencies which humans cannot hear in stressful situations—such as when they experienced a lack of water or their stems were cut. The team identified the sounds with microphones placed around 10 centimeters (around four inches) away from the plants, though the scientists say the noises could potentially be heard several feet away by some mammals and insects, such as mice.

Plants exposed to drought stress have been shown to experience cavitation (空化现象)— a process where air bubbles (气泡)form, expand and explode inside tissue that transports water. These explosions produce sound, but they have only ever been recorded using devices directly connected to the plants. The latest study, meanwhile, is the first to identify plants making sounds which can be detected over a distance. And the researchers say that cavitation could potentially be the source of these sounds.

The team detected the tomato plants made 35 sounds an hour on average when they were exposed to drought conditions, while the tobacco plants produced 11. When the stems of the plants were cut, the tomato plants made 25 sounds an hour on average and the tobacco plants produced 15. As a comparison, unstressed plants made less than one sound hour on aver-age, according to the study.

The team say that while they only tested tomato and tobacco. It's possible that other plants could also produce sounds, adding that the latest findings could have implications for agriculture. ''Plant sound emissions could offer a novel way for monitoring crops' water state—a question of vital importance in agriculture, '' the authors wrote in the study. ''More Precise irrigation can save up to 50 percent of the water consumption and increase the output, with dramatic economic implications. ''

''According to Anne Visscher from the Royal Botanic Gardens, Kew, in the U. K., the idea that the sounds could be used in precision agriculture is 'practical' though she urges caution regarding the Israeli team's suggestion that other animals could hear the sounds at a distance, '' New Scientist reported.

1.What do the Israeli scientists find about plants?

A.Stressed plants tend to lack water.

B.Some plants can understand humans' sounds.

C.Stressed plants can make more frequent sounds.

D.Some mammals and insects can communicate with plants.

2.What can we learn about cavitation?

A.It may contribute to the plants' sounds.

B.It may lead to plants experiencing drought.

C.It is determined by the number of air bubbles.

D.It was identified and recorded for the first time.

3.How many sounds do the tomato plants make per hour on average when cut?

A.11. B.15.

C.25. D.35.

4.What's Anne Visscher's attitude to applying the study to agriculture?

A.Supportive. B.Cautious.

C.Reserved. D.Opposed.