题目内容：

    3D printing is a recent technological development that has started making its way into the marketplace. It is a way of making 3D objects from computer models. 3D printing works by adding together layers of material. This pattern is repeated until the layers form a shape for almost any purpose. The almost unlimited possibility of 3D printing is quickly leading to a revolution in how things are made and produced. As with most technology, 3D printing may help to create things that could benefit humans. However, it could also be used to create things that could harm other people.

One of the promising aspects (方面) of 3D printing is that it may help doctors treat patients in need. Currently, 3D printing is being used to create prostheses (假体) that helps replace missing noses and eyeballs, thus greatly cutting down on the usual wait time for a new prostheses. Dentists are also using 3D printers to create custom toothbrushes for patients’ teeth. The toothbrush fits a person's teeth well, which means that they get a much cleaner mouth than with regular toothbrushes. Many scientists see the potential for 3D printing to create replacement organs for people who need organ transplants. This would save lives as it remove the need for such patients to wait for an organ donation (捐献).

Although many people believe 3D printing is a positive technology that could help humans, it may also have the opposite effect. There is a recent controversy (争议) about the ability of 3D printing to produce arms such as guns. Recently, one organization announced the plans to produce a 3D plastic gun. Anyone with the proper technology and with the determination to make a gun could potentially do so. Will the future of 3D printing provide hope or danger to humans?

1.According to the article, how does 3D printing work?

A.It helps companies enter the marketplace.

B.It adds together layers of material together to make a shape.

C.It uses 3D objects to make computer models.

D.It uses printers to make different models of computers.

2.According to the article, what is one possible future benefit of 3D printing?

A.It may help to prevent deaths. B.It can create controversy.

C.It can make a toothbrush. D.It could produce computers.

3.Which paragraph talks about the controversial aspects of 3D printing?

A.Paragraph 1. B.Paragraph 2.

C.Paragraph 3. D.All of the above.

4.What can be inferred from the article?

A.It is not yet known whether there will be more benefits than dangers in 3D printing.

B.Most of companies will start to use 3D printing technology in the future.

C.Soldiers will benefit greatly from advances in 3D printing.

D.The government will probably forbid 3D printing because it is too dangerous.