Does nature need help from humans? Some scientists say yes. They say that it is important that humans work to
save plants and animals. Many are in danger. Scientists want to move them to areas where they will be safer.
However, other scientists are worried. Sometimes this can change nature and cause unexpected chain reactions
Introducing a new species into an environment can lead to harmful results. Two decades ago, zebra mussels were
put into the Great Lakes. The species is now taking over the lakes. It is choking out other species in the waters

Helping nature can be
A.awkward
B.peaceful
C.difficult
D.tiring