The scientists who re-engineered the plastic-eating enzyme（酶）PETase have now created a new enzyme called "cocktail" ，which can digest plastic up to six times faster.
PETase breaks down PET back into its building blocks,creating an opportunity to recycle plastic and reduce plastic pollution.PET is the most common thermoplastic（热塑性塑料）used to make single-use drinks bottles,which takes hundreds of years to break down in the environment,but PETase can shorten this time to days.The initial discovery set up the prospect of a revolution in plastic recycling,creating a potential low-energy solution to tackle plastic waste.
Now,the same trans-Atlantic team have combined PETase and its "partner"，a second enzyme called MHETase,to generate much bigger improvements：simply mixing PETase with MHETase doubled the speed of PET breakdown,and engineering a connection between the two enzymes to create a "super-enzyme"，increased this activity by a further three times.
The team was co-led by the scientists who engineered PETase,Professor John McGeehan and Dr Gregg Beckham.Professor McGeehan said： "Gregg and I were chatting about how PETase attacks the surface of the plastics and MHETase chops things up further,so it seemed natural to see if we could use them together.Our first experiments showed that they did work better together,so we decided to physically link them. It took a great deal of work,but it was worth the effort - we were delighted to see that our new enzyme is up to three times faster than the separate enzymes."
The original PETase enzyme discovery indicated the first hope that a solution to the global plastic pollution problem might be within grasp,though PETase alone is not yet fast enough to handle the tons of PET bottles.Combining it with a second enzyme,and finding together they work even faster,means another leap forward has been taken towards finding a solution to plastic waste.PETase and the new combined MHETase-PETase both work by digesting PET plastic.This allows for plastics to be made and reused endlessly,reducing our reliance on fossil（化石）resources.



What can we learn about "cocktail" from the text？ ______

A. It doubles the breakdown of plastics.
B. It takes hundreds of years to break down.
C. It contributes to breaking down plastic quickly.
D. It deals with the plastic waste three times faster.

What is the second paragraph mainly about？ ______

A. A new study of PET.
B. The breakdown of PET.
C. The discovery of PETase.
D. The functions of PETase.

What does the underlined word "It" in Paragraph 4 refer to？ ______

A. Co-leading the trans-Atlantic team.
B. Combining PETase and MHETase.
C. Attacking the surface of the plastics.
D. Talking about conducting experiments.

What can we infer from the text？ ______

A. PET pollution is no longer a difficult problem to deal with.
B. New enzyme is speeding up our reliance on fossil resources.
C. MHETase-PETase makes the world free from plastic pollution.
D. Plastic-eating enzyme "cocktail" promises new hope for plastic waste.