Around the world, honeybee groups are dying in huge numbers: About one-third of nests collapse each year. For bees and the plants they pollinate (授粉) — as well as for beekeepers, farmers, honey lovers and everyone else who appreciates this marvelous social insect — this is a catastrophe.
Honeybee collapse has been particularly worrying because there is no one cause, but rather a thousand little cuts. The main elements include the mixed impact of pesticides (杀虫剂) applied to fields, as well as pesticides applied directly into nets to control bugs, pests and diseases; nutritional shortages caused by vast acreages of single-crop fields that lack diverse flowering plants; and commercial beekeeping itself, which destroys groups by moving most bees around the country multiple times each year to pollinate crops.
The real issue, though, is not the volume of problems, but the interactions among them. Here we find a major lesson from the bees that we ignore at our risk: the concept of synergy (协同作用), where one plus one equals three, or four, or more. A typical honeybee colony contains remains from more than 120 pesticides. Alone, each represents a benign dose (良性剂量). But together they form a poisonous soup of chemicals whose interplay (相互作用) can greatly reduce the effectiveness of bees’ immune systems, making them easier to suffer from diseases.
Observing the death of honeybees should warn us that our own well-being might be similarly threatened, and the widespread collapse of so many groups presents a clear message: We must demand that our regulatory authorities require studies on how exposure to low dosages of combined chemicals may affect human health before approving compounds.
Bees also provide some clues to how we may build a more collaborative relationship with the services that ecosystems can provide. Bees could offer some of the pollination service needed for agriculture. People discovered that crop harvests, and thus profits, are maximized if some cropland are left uncultivated for bees. Meanwhile a variety of wild plants means a healthier, more diverse bee population, which will then move to the planted fields next door in larger and more active numbers.
Which of the following is NOT the cause that leads to bees dying?

A．Lack of nutrition from enough diverse flowering plants.

B．The pests and diseases of the bees.

C．The beekeepers’ destroying without intention

D．The pesticides applied to crops.

By saying “one plus one equals three, or four, or more” in Paragraph 3, the author means that ____.

A．bees united mean they are much more powerful

B．bees united mean they are much more poisonous

C．pesticides mixed mean they are much more poisonous.

D．pesticides mixed mean they are much more effective.

The lesson people can learn from bees dying is that ____________.

A．medicine is as powerful as pesticide

B．our health might be threatened by pesticides

C．we should protect bees by reducing the usage of pesticides

D．medicine may be harmful to us when used together

What is the last paragraph mainly about?

A．Keeping a balance with nature is important

B．More plants mean more and healthier bees.

C．Bees are very important to agriculture.

D．Bees can bring in good higher profits to farmers