TPO 11 MINERALS AND PLANTS - 英檢

Paragraph 6:
Only recently have investigators considered using these plants
to clean up soil and waste sites that have been contaminated by toxic levels
of heavy metals – an environmentally friendly approach known as
phytoremediation. This scenario begins with the planting of hyper
accumulating species in the target area, such as an abandoned mine or an
irrigation pond contaminated by runoff. Toxic minerals would first be
absorbed by roots but later relocated to the stem and leaves. A harvest of
the shoots would remove the toxic compounds off site to be burned or
composted to recover the metal for industrial uses. After several years of
cultivation and harvest, the site would be restored at a cost much lower than
the price of excavation and reburial, the standard practice for remediation
of contaminated soils. For examples, in field trials, the plant alpine
pennycress removed zinc and cadmium from soils near a zinc smelter, and
Indian mustard, native to Pakistan and India, has been effective in reducing
levels of selenium salts by 50 percent in contaminated soils.



11. It can be inferred from Paragraph6 that compared with standard practices
for remediation of contaminated soils, phytoremediation

1.does not allow for the use of the removed minerals for industrial purposes.
2.can be faster to implement
3.is equally friendly to the environment
4.is less suitable for soils that need to be used within a short period of
time.


答案是四， 想請問大家為什麼是四= =

他不是說"compare with standard practices for remediation" 可是文章沒有說

standard practices for remefiation 比較適合說@@

請大家解答摟 !!!謝謝~

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