题目内容：

    Sharpshooters refer to those who are skilled at firing a gun and accurately hitting what they are aiming at. However, some fish are also called amazing sharpshooters. People wonder how they hit their targets without using tools? By spitting! The fish shoot so accurately that they rarely miss their target.

These amazing fish are archerfish (印度射水鱼).There are several different types of archerfish living in Southeast Asia. They spit at their dinner to catch it. To catch dinner, a fish first sets itself in a certain place, for example just below the surface of the water. It puts the tip of its mouth so it barely breaks through the water. Then, the fish waits for an unsuspecting insect to land on a leaf or branch hanging over the water.

When an unsuspecting, or unknowing insect lands, the fish attacks. The fish squeezes its gill (腮)covers very rapidly, which forces water into the fish's mouth. In the roof of its mouth the fish has a groove (槽）• The fish forms the small groove and its tongue into a narrow tube by pressing its tongue up against its groove. The water forced into the fish's mouth is forcefully pushed out of the fish's moulh through the tube. Archerfish have been known to send a stream up to 5 meters (16 feet). However, archerfish can only shoot insects up to 1-2 meters (3-6 feet) away due to their limited accuracy.

When the unsuspecting insect is hit with a sudden stream of water, it is knocked into or falls into the water. Once in the water, the insect becomes dinner. Archerfish learn how to spit when they are young. They get more accurate with practice. Adult archerfish rarely miss.

Within a meter, archerfish will often spring out of the water and grab an insect in their mouths.

1.Paragraph 1 flinctions as a(n)    .

A. background. B. comment.

C. explanation. D. introduction.

2.Which of the following is the right steps of archerfish’s hunting for an insect?

a. It has its tongue pressed against the roof of its mouth.

b. It gathers water into its mouth by squeezing its gill covers quickly.

c. It shoots a stream of water at the insect above water.

d. It stays underwater for an insect to land nearby.

A. adcb B. dbac

C. dbca D. adbc

3.If an insect is 3 feet away, an archerfish will often to catch it.

A. jump out of the water B. spit a kind of oily liquid

C. shoot a stream of water at it D. push its tongue out of its mouth

4.Archerfish can’t hit insects 5 meters away for the reason that .

A. their eyesight is limited

B. they can’t hit faraway insects precisely

C. their mouths are under the surface of water

D. the longest distance they can hit is at most 5 meters