how to solve the problem of animals extinction in science

There are several ways to do so:
(i)Place them in zoo so that veterinarian and animal care worker will take care of them.
(ii)Some rare species animals are protected by law so that they are not allowed to be sold illegally.
(iii)No shooting is premitted unless allowance is granted by the government.
(iv)Building up a forest for them to leaves so that any natural enemies will not have any chance to harm them.This also provides a good shelter for them to live.
(v)We, the consumer(消費者), don't buy any products made from rare species animals. There is a rule called supply and demand. If no one buys those products, those businessmen will not kill them again so as to make profit from them.
(vi)Set up a rare animals protect funds so that any organization(s) can have enough money to support their job on protecting those rare animals.
(vii)Educate people not to buy them or to sell them so as to make profit. The power of education is of paramount important.

I hope you will find them good for you.

Animals extinction can not be sloved (as it is impossible to to make those extincted animals alive ). What we can do it to prevent the rare species from extinction.

The cutting trees, the changing of weather pattern, the killing of animals for human consumption are the disruption of the ecological cycle. Some of species are died out.

So, to keep the rare species from alive, it should be a group of responsibilites. The group involves companies , households, individuals. They should work together to maintain the ecological cycle.

not to kill animals which nearly exitinct
protect their living place
promote the protection of rare animal
artificial propagation