Future Perfect Tense

By the end of this century, the planet ___ (become) more polluted.

• will have become

• will have been becoming

By the end of this century, we ___ (cut down) trees in the rainforest for more than two centuries.

• will have cut down

• will have been cutting down

By the end of this century, they ___ (probably not find) a solution to the problems created by climate change.

• probably won't have found

• probably won't have been finding

By the end of this century, scientists ___ (discover) more efficient alternative energy sources.

• will have discovered

• will have been discovering

By the end of this century, experts ___ (invent) new ways to clean up oil spills.

• will have invented

• will have been inventing

By the end of this century, we ___ (build) cities for many years.

• will have built

• will have been building

By the end of this century, ___ (people/realise) that they must find a way to feed the poor in Africa?

• will people have realised

• will people have been realising

By the end of this century, conservationists ___ (discuss) how to help endangered species for a long time.

• will have discussed

• will have been discussing