The baobab tree is sometimes called “the Tree of Life." Baobabs grow in Africa and Australia. They are the most famous trees in Africa. Baobabs have very thick, wide trunks （树干）.Often the trunks have large empty spaces inside.

In South Africa, one famous tree had a hole so large that someone built a bar inside it. People could sit inside and order drinks. That tree was known as the Sunland Baobab. It was more than 1,000 years old. It was the biggest baobab in Africa. But in 2017 it fell down. In 2016, another famous baobab fell down and died. It was called the Chapman tree in Botswana.

A recent study shows that the problem is widespread. Adrian Patrut and his team started studying the baobabs in 2005.The team found bad news. In the past 12 years, “nine of the thirteen oldest and five of the six largest have died,” the report found. Sometimes parts of the tree didn't die. But the “oldest parts” did.

Experts aren't sure what is causing the baobabs to die. They think it may be related to climate change. But more research is needed to prove it.

The largest trees need more water and food than smaller baobabs. Patrut thinks that is what puts them at greater danger. More heat and less rainfall could have a big influence on the trees.

In Zimbabwe a fungus（真菌）turns baobabs black before they die. But Patrut's study didn't find signs of a widespread disease. No matter the cause, the loss is huge.

Baobabs are amazing. They are a major food source for people. The trees grow white flowers that open at night. Bats spread the pollen（花粉）and help the trees grow fruit. Their white fruit is called monkey bread. People use it as food and to make cool drinks. People make paper, cloth, and even drugs from baobab bark（树皮）.

【小题1】What do we know about the Sunland Baobab?

A．It was the biggest baobab in Australia.

B．It was the oldest tree in the world.

C．It fell down in 2016 in Botswana.

D．It once had a bar inside it

【小题2】What did Patrut's study find?

A．More baobabs are dying,

B．Old baobabs are going to disappear.

C．Trees worldwide have common problems.

D．Trees' living environment is getting worse.

【小题3】As for what's killing baobabs, experts ______

A．are certain human activities put them in danger

B．are sure it is because of climate change

C．have proved disease is the main cause

D．need to carry out more studies

【小题4】What is the main idea of the last paragraph?

A．The great uses of baobab trees

B．The danger of losing baobab trees.

C．How baobab trees help other plants

D．The importance of protecting the environment.