While on a family canoe trip on the Fox River a few years ago ，Grant and Colton Shepard were disturbed by what they saw in the water.“We were there to enjoy the ____，”says Grant,11，“____we saw a lot of litter (垃圾) .”
The brothers，who live in Riverside，Illinois，went home and took action.They ____the Illinois Department of Natural Resources，____ to monitor local rivers and streams carefully.They ____training workshops to become familiar with the organisms (微生物) that are found in local____.
Ever since，the two boys have been taking weekly ____ from two rivers.They study them to make certain that the underwater ecosystem is ____.Sometimes they find strange things.“We ____discovered a big picnic table that had ____underwater！” says Grant.
It’s not just rivers that these kid volunteers____.They have devoted themselves to keeping their environment____balanced.“In the future，we’re going to need more resources.____we protect them now，they won’t be there for us，”says Colton,14.
Every year，____their campaign for a cleaner world, the brothers____ at least 100 days without using a car.Their purpose is to cut down on the ____ gases that cars give off into the air.
The brothers have also been active in helping ____ Illinois’ precious grassland.For the past two years，they have spent ____ one Saturday a month clearing away nonnative plants from a 100acre rare oak (橡木) grassland.“The plants and bushes ____our heritage because they prevent the old oaks from growing ____，”says Grant.

A．garden B．grass C．beauty D．trip

A．because B．so C．though D．but

A．contacted B．reminded C．informed D．interviewed

A．preparing B．offering C．advising D．agreeing

A．produced B．provided C．attended D．held

A．forests B．lakes C．waters D．schools

A．wastes B．samples C．polluters D．liquids

A．in order B．in place C．in danger D．in balance

A．never B．often C．once D．seldom

A．put B．deserted C．sunk D．left

A．pick out B．care about C．look out D．take over

A．slightly B．regularly C．totally D．finally

A．Even if B．As long as C．Before D．Unless

A．for the purpose of B．as a result of C．as part of D．as well as

A．walk B．run C．choose D．go

A．extra B．harmful C．useless D．various

A．decorate B．plough C．design D．restore

A．at least B．by turns C．as usual D．at most

A．destroy B．threaten C．change D．replace

A．rightly B．nicely C．properly D．separately