题目内容：

Scientists are preparing to launch the world's first machine to clean up the planet's largest mass of ocean plastic.

The experts believe the machine should be able to collect half of the detritus in the patch – about 40,000 metric tons – within five years. In the past few weeks they have been busy welding together giant tubes that will sit on the surface of the sea and form the skeleton of the machine, creating the largest floating barrier ever made。

The system, originally dreamed up by Mr. Slat, will be shipped out this summer to the Great Pacific Garbage Patch, between Hawaii and California, and which contains an estimated 1.8 trillion pieces of plastic. It will be the first ever attempt to tackle the patch since it was discovered in 1997.

Mr. Slat was 16 and still at school when he was diving in Greece and first saw for himself the amount of plastic polluting the sea. “There were more bags than fish down there,” he recalls. Two years later he came up with a solution, quit university after six months and set up The Ocean Cleanup as a company. Mr. Slat, 23, says the first plastic to arrive on shore will be a major milestone. “We as a humanity created this problem, so I think it's our responsibility also to help solve it,” he said.

The Great Pacific Garbage Patch (GPGP) spans 617,763 sq miles - more than twice the size of France, and contains at least 79,000 tons of plastic, research found last month. Most of it is made up of “ghost gear” – parts of abandoned and lost fishing gear, such as nets and ropes – often from illegal fishing vessels.

Ghost gear kills more than 100,000 whales, dolphins and seals each year, according to scientific surveys. Seabirds and other marine life are increasingly being found dead with stomachs full of small pieces of plastic. Creatures eat plastic discarded in the sea thinking it’s food but then starve to death because they are not feeding properly. Others are trapped and die of starvation or are strangled or suffocated by ghost gear.

1.What does the underlined word in the first paragraph probably mean?

A. waste.    B. ocean.

C. system.    D. machine.

2.According to the passage, most of the Garbage in Pacific is made up of _____ .

A. fishing vessels

B. dolphins and seals

C. giant tubes

D. abandoned fishing gear

3.why do some creatures in The Great Pacific Garbage Patch die of starvation?

A. because they were killed by Ghost gear.

B. because they were suffocated by ghost gear.

C. because they didn't like eating plastic.

D. because they are not feeding properly.

4.What is the main idea of the Passage?

A. news about the first machine to clean up ocean plastic.

B. report about the death of marine life

C. information about ocean plastic.

D. the reason for inventing a machine.