题目内容：

    Heart disease is one of the major killers in the world today. Many who suffer from it must have heart transplants. However, it’s difficult to get a suitable heart donation, and even if a patient survives the wait, his or her body often rejects the heart.

But there is now new hope for sufferers of heart disease. According to a study published in the journal Advanced Science, researchers from Israel’s Tel Aviv University printed a 3D human heart on April 15.

“This is the first time anyone anywhere has successfully engineered and printed an entire heart,” professor Tal Dvir told CNN. Unlike the previous 3D-printed heart structure, the new heart is complete with cells, blood vessels, chambers and other structures a heart needs to function normally. But scientists still have more to figure out before the 3D-printed heart can be fitted into the body. For one thing, the experimental heart is only the size of a thumb. And, although it can contract like a muscle, it cannot pump out blood like a real one. At present, the heart prototype is like a tiny airplane that has all of the right parts, but can’t fly.

However, the development is still regarded as a major breakthrough in medicine.

In the experiment, the researchers turned human fat tissue into human heart tissue with stem cell technology. The tissue was then turned into “bio-ink” for a 3D printer to ensure that tissue in the heart came from the patients themselves. So ideally, if it were to be placed in the body of someone in need of a transplant, there would be less risk of organ rejection. “Patients will no longer have to wait for transplants or take medications to prevent their rejection,” researchers told USA Today. “Instead, the needed heart  will be printed, fully personalized for every patient.”

But the scientists think that 3D printing can be used to create other human organs. They foresee a time when the 3D printing of organs will be an everyday medical practice. “Maybe, in 10 years, there will be organ printers in the finest hospitals around the world and these procedures will be conducted routinely,” Dvir said.

1.Why do scientists have to do further research before fitting the 3D-printed heart into the body?

A.Because the heart is incomplete.

B.Because the heart can’t pump out blood.

C.Because the heart is an airplane that can’t fly.

D.Because the heart can’t contract like a muscle.

2.What can we infer from the last two paragraphs?

A.The needed heart will be printed to meet every patient’s need.

B.The 3D printing of organs will be an unusual medical practice.

C.Dvir has a negative attitude towards the future of organ printers.

D.Patients will need medicines to stop their rejection for their heart transplant.

3.What can serve as the best title for the passage?

A.Organ printers in the hospitals.

B.How to get a suitable heart donation.

C.Heart disease: one of the major killers.

D.A 3D-printed heart: new hope for heart disease sufferers.