The health of millions could be at risk because medicinal plants are being used up.These plants are used to make traditional medicine，including drugs to fight cancer.“The loss of medicinal plants is a quiet disaster，”says Sara Oldfield，secretary general of the NGO Botanic Gardens Conservation International.
Most people worldwide (including 80 percent of all Africans)rely on herbal medicines(草药)which are got mostly from wild plants.But some 15,000 of the 50,000 medicinal species are under threat of dying out，according to a report from the international conversation group Plantlife.Shortages have been reported in China，India，Kenya，Nepal，Tanzania and Uganda.
Overharvesting does the most harm，though pollution and competition from invasive(侵略性的)species are both responsible.“Businessmen generally harvest medicinal plants，not caring about sustain ability，”the Plantlife report says.“Damage is serious partly because they have no idea of it，but it is mainly because such collection is unorganized.” Medicinal trees at risk include the Himalayan yew and the African cherry，which are used to treat some cancers.
The solution，says the report's author，Alan Hamilton，is to encourage local people to protect these plants.Ten projects studied by Plantlife in India，Pakistan，China，Nepal，Uganda and Kenya showed this method can succeed.In Uganda the project has kept a sustainable supply of lowcost cancer treatments，and in China a public run medicinal plant project has been created for the first time.
“Improving health，earning an income and keeping cultural traditions are important in encouraging people to protect medicinal plants，”says Hamilton.“You have to pay attention to what people are interested in.” Ghillean Prance，the former director of the Royal Botanic Gardens at Kew in London，agrees that medicinal plants are in need of protection.
“Not nearly enough is being done，”he told New Scientist.“We are destroying the very plants that are of most use to us.”
What is the passage mainly about?

A．The function of medicinal plants.

B．The importance of traditional medicine.

C．More and more people rely on herbal medicines.

D．The dangerous situation of medicinal plants and ways of protecting them.

Which of the following is TRUE according to the passage?

A．About 30% of medicinal species are at risk of dying out.

B．Medicinal plants are mainly used to treat cancers.

C．80% of African countries are reported to be short of medicinal plants.

D．The problem of the loss of medicinal plants appeared suddenly.

What contributes most to the loss of medicinal plants?

A．A lack of knowledge of sustainability.

B．Invasion by other species.

C．Environmental pollution.

D．Improper harvesting.

What is a useful method of protecting medicinal plants?

A．Improving people's health.

B．Letting people earn more.

C．Working together with the government.

D．Persuading the locals to protect them.