题目内容：

    We've known for years that plants can see,hear,smell and communicate with chemicals.Now, reported New Scientist,they have been recorded making sounds when stressed.

In a yet-to-be-published study, Itzhak Khait and his team at Tel Aviv University, in Israel, found that tomato and tobacco plants can make ultrasonic(超声的)noises. The plants "cry out" due to lack of water,or when they are cut. It's just too high-pitched(音调高的）for humans to hear.

Microphones placed 10 centimeters away from the plants picked up sounds in the ultrasonic range of 20 to 100 kilohertz(干赫兹)。Human hearing usually ranges from 20 hertz to 20 kilohertz."These findings can change the way we think about the plant kingdom,”they wrote.

On average,"thirsty"tomato plants made 35 sounds an hour,while tobacco plants made 11. When they were cut,tomato plants made an average of 25 sounds in the following hour,and tobacco plants 15.Unstressed plants produced less than one sound per hour,on average.

Perhaps most interestingly,different types of stress led to different sounds.The researchers trained a machine-learning model to separate the plants' sounds from those of the wind,rain and other noises of the greenhouse.In most cases,it correctly recognized whether the stress was caused by dryness or a cut.Water-hungry tobacco appears to make louder sounds than cut tobacco,for example.Although Khait and his colleagues only looked at tomato and tobacco plants,they think other plants also make sounds when stressed.

If farmers could hear these sounds,said the team,they could give water to the plants that need  it most.As climate change causes more droughts,they said this would be important information for farmers. "The sounds that drought-stressed plants make could be used in precision(精准) agriculture, "said Anne Visscher at the Royal Botanic Gardens,Kew,in the UK.

Khait's report also suggests that insects can hear the sounds up to 5 meters away and respond. For example,a moth(蛾子）may decide not to lay eggs on a water-stressed plant.Edward Farmer. at the University of Lausanne,Switzerland,is doubtful.He said that the idea of moths listening to plants is"a little too speculative”。

If plants are screaming(尖叫）for fear of their survival,maybe we should be glad we can't hear them.

1.Paragraph 3 mainly explains_______.

A.where humans differ from plants

B.how the research was carried out

C.what the findings of the study are

D.why humans can't hear the cries of plants

2.Which of the following is TRUE according to the study?

A.All plants make sounds when they feel hungry.

B.Stressed plants make more sounds than unstressed ones.

C.Tobacco plants are more afraid of thirsty than being cut.

D.The more stressed a plant is,the louder sounds it makes.

3.What does the underlined word"speculative"in Paragraph 7 probably mean?

A.Surprising.

B.Uncertain.

C.Incorrect.

D.Unique.

4.What is the best title for the text?

A.Deaf humans

B.Stressed plants

C.Silent screams

D.Precision agriculture