Iman, the last Sumatran rhino(犀牛) in Malaysia, died in 2019 — bringing the endangered species one step closer to extinction. Now, Malaysian scientists are hoping to use tissues and cells from Iman and other dead rhinos to bring the population back.

“Before the three rhinos (the last survivors in Malaysia) died, we got their cells, and the cells are still alive — which is why I’m quite confident,” Dr. Lokman said. “If we don’ t have any cells, or have just tissue that isn’t living anymore, we wouldn’t be able to do anything. But now we have a living thing that we can use.”

The cells came from the rhinos’ hearts, lungs and brains. What is the most important is that the team collected stem cells (干细胞). One possible approach is to develop these stem cells into an egg（卵子）and sperm (精子), to create an embryo (胚胎) that will be placed into a surrogate mother (代孕母亲). She will likely be another rhino, either a Sumatran rhino from another country or another species. The other method is to take the egg of a surrogate animal, remove the nucleus (细胞核), and join it with a Sumatran rhino’s body cell. This technique was famously used to clone Dolly the sheep in 1996. Dr. Lokman and his colleagues are trying both ways. The team is still in the early stages; next, they need to find a suitable surrogate female.

Sumatran rhinos are listed as critically endangered by the World Wildlife Fund. There are less than 80 alive in Indonesia and Thailand. The fall in the population was first caused by hunting. Later, the situation was worsened by the loss of habitats and human activity. Unfortunately, there are now only five remaining rhino species worldwide, and all are threatened. Some sub-species have already died out; the western black rhino was declared extinct in 2013. And it is a pity that the last male northern white rhino died in 2019.

【小题1】What makes it possible for the team to bring the Sumatran rhinos population back?

A．They have collected three rhinos living cells.

B．They have carried out similar experiments before.

C．There is a baby Sumatran rhino living in Malaysia.

D．There are still some cells alive in the dying rhino.

【小题2】What do the two methods have in common?

A．Both have been used for Dolly.	B．Both change the cell’ s nucleus.
C．Both involve a surrogate female.	D．Both rely on the Sumatran rhinos’ stem cells.

【小题3】What feeling does the author express in the last paragraph?

A．Her admiration for cloning technology.

B．Her satisfaction with the scientists’ efforts.

C．Her disappointment at protection measures.

D．Her deep worry about the rhino population.

【小题4】What’s the main idea of the passage?

A．Last Sumatran rhino in Malaysia has died.

B．Scientists hope to clone Sumatran rhinos.

C．Stem cells are giving birth to new rhino babies.

D．Sumatran rhinos are listed as critically endangered.