There are many gardening tips．Some suggest playing music for your houseplants，having conversations with them，or even giving them a gentle touch now and then．Most of these practices are probably more for the benefit of the gardener than the garden，and generally harmless enough but except the last one．Your plants really dislike it when you touch them．
   A new study out of the La Trobe Institute for Agriculture and Food has found that most plants are extremely sensitive to touch，and even a light touch can significantly stunt（阻礙） their growth． "The lightest touch from a human，animal，insect，or even plants touching each other in the wind，can cause a huge gene response in the plant，" Jim Whelan，who led the new study，said． "Within 30 minutes of being touched，10% of the plant's genome（基因組） is changed．This involves a huge expenditure（消耗）of energy which is taken away from plant growth．If the touching is repeated，then plant growth is reduced by up to 30%．"
   Whelan and his team are still trying to find out why plants respond，at the genetic level，so strongly．They do have some theories，however．We know that when an insect lands on a plant，genes are activated（激活） preparing the plant to defend itself against being eaten，" said Dr．Yan Wang，co-author of the study．
   Until more research is done，it's just a guess at this point．Still，the findings might already lead to new methods for how agriculturalists deal with their crops，to best promote healthier growth．
   It's worth noticing that while the study found that plants often respond to just a single touch in negative ways，it's really repeated touching that causes lasting stunted growth．That's because the plants are looking for patterns in the touching，to tell harmful touch from random touch．So it doesn't matter if you accidently brush up against a bush during a walk through the woods．

（1）How is the passage mainly developed？

D

D

A．By comparing
B．By giving examples
C．By listing numbers
D．By showing results of studies
（2）Why can touching stunt a plant growing according to the study？

A

A

A．It leads to the plant's energy expenditure．
B．It makes the plant sensitive to threats．
C．It causes a genetic disorder in the plant．
D．It prevents the plant absorbing nutrients．
（3）What's the importance of the study by Whelan and his team？

B

B

A．It gives us more useful gardening tips．
B．It helps find ways to ensure plants' healthy growth．
C．It contributes to the further study on genes．
D．It uses data to warn people not to touch plants．
（4）What is the passage mainly about？

C

C

A．Something is done to help plants grow．
B．Plants' genome can be changed easily．
C．Plants don't really like to be touched．
D．What we do every day may destroy plants．