Future Perfect Tense

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

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

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

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

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

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

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

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