In the recently opened Our Broken Planet exhibition in London's Natural History Museum，a small piece of dark material covered with faint holes is on show in a display container.The nodule（小塊）could easily be mistaken for coal，but its true nature is much more interesting.
    The nodule is a combination of metals and oceanographers have discovered trillions of them on Earth's ocean floors.Each is rich in some of the most important elements for making the electric cars，wind turbines and solar panels that we need to replace the carbon-emitting motors，power plants and factories now damaging our climate.
    These nodules could therefore help humanity save itself from the ill effects of global warming，argue mining companies who say their exploitation should be rated an international priority.By mining up chunks（塊）from the deep we can slow the burning of our planet's surface.
    "We desperately need substantial amounts of metals contained by these nodules to build electric cars and power plants，" says Hans Smit，chief executive of Florida's Oceans Minerals，which has announced plans to mine for nodules. "We cannot increase land supplies of these metals without having a significant environmental impact.It's our only alternative."
    Other researchers disagree，however.They say mining deep-sea nodules would be disastrous for our already stressed，plastic-ridden，overheated oceans.Delicate，long-living residents of the deep—shells，fish，corals and squids—would be erased by mining.At the same time，mud with poisonous metals would be sent upwards to disturb marine food-chains.
    "It is hard to imagine how seabed mines could workably operate without destroying the ocean species，" says UK marine biologist Helen Scales，a view shared by David Attenborough，who has called for a pause on all deep-sea mining plans. "In this case it means the destruction of an ecosystem，an issue worth the best attention from every entity（實體）involved." he says.
    For better or worse，these mineral nodules are going to play a critical role in determining our future—either by releasing us from our current ecological headaches or by stimulating even more fatal outcomes.

（1）What is the nodule on display？

C

C

A．An attractive artificial artwork.
B．A difficult-to-tell chunk of coal.
C．An oceanic piece rich in metals.
D．A container for electric materials.
（2）What does "our only alternative" underlined in paragraph 4 refer to？

D

D

A．Metals for power plants.
B．Land supplies of metals.
C．Massive production of electric cars.
D．Underwater mining for specific metals.
（3）Which word best describes David's attitude to deep-sea nodule exploitation？

A

A

A．Disapproving.
B．Skeptical.
C．Objective.
D．Conservative.
（4）Why do the mineral nodules play an important role in determining our future？

B

B

A．They can be used both for good and for bad.
B．Their exploitation can bring opposing effects.
C．They contain beneficial and harmful elements.
D．Their exploiters cannot reach agreement till now.