已知关于x，y的方程组mx+ny=72mx-3ny=4的解为x=1y=2，求m，

阅读理解

     Some plants get so hungry they eat flies, and even small frogs. What's more amazing is that these plants occur naturally (in special environments) in every state. In fact, they're found on every continent except

Antarctica.

     You've probably seen a Venus' flytrap -- a small plant, which grows 6 to 8 inches tall in a container. At the end of its stalks (茎) are leaves that act like traps (陷阱). Inside each trap is a lining of tiny hairs. When an insect lands on them, the traps suddenly shut. Over the course of a week or so, the plant feeds on its

catch.

     The Venus' flytrap is just one of more than 500 species of meat-eating plants, says Barry Meyers-Rice, the editor of the International Carnivorous Plant Society's Newsletter. He states although you might have

read some science-fiction stories, no meat-eating plant does any danger to humans.

Barry says a plant is meat-eating, only if it does all four of the following: "attract, kill, digest, and absorb"

some form of insects. Meat-eating plants look and act like other green plants -- well, most of the time.

All green plants make sugar to produce food. What makes meat-eating plants different is their special

leaves, which need insects for one reason: nitrogen (氮). Nitrogen is a nutrient that they can't obtain any

other way. Why?

     Almost all green plants on our planet get nitrogen from the soil. Meat-eating plants can't. They live in

places where nutrients are hard to get from the soil because of its acidity. So they've come to rely on

getting nitrogen from insects and small animals. In fact, nutrient-rich soft is poisonous to meat-eating plants. Never fertilize (施肥) them! But don't worry, either, if they never seem to catch any insects. They can

survive, but they'll grow very slowly.

1. According to the passage, a Venus' flytrap ______.

A. is a small plant which grows in a container

B. is a kind of plant which gets hungry easily

C. can trap and feed on some form of insects

D. can only grow 6-8 inches tall

2. From the passage, we can infer that ______.

A. meat-eating plants are found nowhere else except Antarctica

B. all green plants get nitrogen from the soil

C. meat-eating plants endanger humans in science-fiction stories

D. the nutrient-poor soil is beneficial to meat-eating plants

3. Meat-eating plants grow very slowly, ______.

A. so you'd better fertilize them

B. probably because the supply of nitrogen is cut off

C. simply because they can't absorb nitrogen from the soil

D. and then they will die slowly

4. Which of the following is true?

A. Meat-eating plants look and act like other green plants.

B. It's hard to get nutrients in the soil when acidity is high.

C. The Venus' flytrap eats flies to get nutrient from them.

D. Green plants make sugar at night.

企业采用固定股利支付率的股利政策，其结果可能有( )。

A．可使得股利的发放随着企业经营业绩的好坏而上下波动

B．容易造成股利的支付与盈余脱节

C．容易造成企业各年股利不稳定，出现较大波动

D．有利于维持企业股价的稳定

E．有利于保持最低的资金成本

求图所示电路中开关S在“1”和“2”位置时的时间常数。

教师的职业特点决定了教师的素质结构中必须具备（）

A.知识要素

B.品德要素

C.审美素养要素

D.人格魅力

E.创美能力

炎黄艺术馆是中国第一座大型民办公助的现代艺术博物馆，是由著名画家黄胄筹办的。（）