"It can't be done." Boyan Slat heard this over and over when he first suggested a way to clean up millions of tons of plastic polluting our oceans.
   Slat was on a diving（潛水）trip in Greece three years ago when he was troubled by plastic. "There were more plastic bags than fishes，"he says."That moment I realized it was a huge problem and that environmental problems are really the biggest problems we will face."
   That fall，Slat，then 17，decided to study plastic pollution as part of a high school project.Soon，Slat learned that no one had yet thought of useful ways to clean up all the rubbish.Most people wanted to"fish"up the plastic using ships with nets---which might need more than 1，000 years，cost too much，and leave sea life along with the rubbish.
   Slat decided to avoid these problems：a solar-powered system（太陽能系統(tǒng)）using a moving plastic tube（管）which will go around the rubbish and collect it.Wind and waves will push the rubbish to the tube.A ship will pick up the rubbish and take it back to the land.
   Slat organized a team of volunteers for the Ocean Cleanup，which has about 100 members.
   Over the next three to four years，Slat will continue to test whether his project is good enough or not.
   Use words with proper meanings and grammatical rules to fill in the blanks.

（Only one word for one blank.）
（1）Slat first suggested cleaning up millions of tons of

plastic

plastic

to stop

polluting

polluting

the ocean.
（2）When Slat was diving in Greece，he found there were

fewer

fewer

fishes

than

than

plastic bags.
（3）"Fishing"up the plastic might need a

long

long

time and

cost

cost

too much.
（4）Slat hoped the rubbish would be pushed to the tube by

wind

wind

and

waves

waves

.
（5）It will

take

take

Slat and his team over three to four years to test

whether

whether

his project is good enough or not.