1 . A hungry fly speeds through a forest. It smells nectar (a liquid that insects feed on) and lands on a green leaf. It starts to drink the sweet liquid. Suddenly, the fly's world turns green. The two sides of the leaf close against each other. Long green teeth lock together around it. The fly has been caught by a Venus flytrap. There is no escape.

The Venus flytrap is perhaps the most famous killer plant. However, scientists have only recently started to understand how it hunts and eats. After years of study, plant scientist Alexander Volkov believes he now knows the Venus flytrap's secret. “This,” says Volkov," is an electrical plant."

There are three small hairs along each of the Venus flytrap's two leaves. When an insect touches a hair, it creates an electrical signal in the leaf. The insect can continue feeding—for now. But if it touches another hair within 20 seconds, the trap snaps shut. This system allows the plant to tell the difference between a drop of water, for example, and a moving creature.

Once trapped, an insect has little chance of survival. Instead of nectar, the Venus flytrap now releases a different liquid —one that slowly eats away at the insect. Ten days later, almost nothing is left. The plant's leaves open again, and the Venus flytrap is ready for its next meal.

Besides the Venus flytrap, there are around 700 species of killer plants around the world. Some are deadly. Sundews catch insects using a sticky liquid on the end of long hairs. A butterwort's leaves are covered with tiny, gluey hairs that trap small insects. Pitcher plants have long tubelike leaves into which insects fall and die. Some pitcher plants are large enough to catch and eat small animals like frogs and mice.

1. What is special about the Venus flytrap?

A．Its trap closes very slowly.	B．It has to feed on flies.
C．It produces electrical signals.	D．It just makes one kind of liquid.

2. What is the purpose of Paragraph 4?

A．To explore how the insect survives.

B．To explain how the Venus flytrap works.

C．To describe different types of killer plants.

D．To introduce an experiment carried out on a plant.

3. Which plant does not use hairs to catch insect?

A．The sundew.	B．The butterwort.
C．The pitcher plant.	D．The Venus flytrap.

4. What might be discussed in the following part?

A．What meals a Venus flytrap prefers.

B．What the features of deadly plants are.

C．Where the deadly plants are found.

D．How other killer plants catch insects.