By“we don’t have 500 million years to wait”(Line 4，Para．6)，the author suggests that_____.A.we have no enough time to allow the earth to recover from damagesB.we have no enough time to witness the evolution of a speciesC.it’s urgent for humans to take steps to prevent global warmingD.its necessary for humans to stop maltreatment of the planet
A.6)，the
B.
A.we
C.we
D.it’s
E.its