题目内容：

    Large gatherings such as weddings and conferences can be socially overwhelming. Pressure to learn people's names only adds to the stress. A new facial-recognition app could come to the rescue, but privacy experts recommend proceeding with caution.

The app, called Social Recall, connects names with faces via smartphone cameras and facial recognition, potentially avoiding the need for formal introductions. “It breaks down these social barriers we all have when meeting somebody," says Barry Sandrew, whose start-up, also called Social Recall, created the app and tested it at an event attended by about 1,000 people.

After receiving an invitation to download Social Recall from an event organizer, the user is asked to take two selfies and sign in via social media. At the event, the app is active within a previously defined geographical area. When a user points his or her phone camera at an attendee's face, the app identifies the individual, displays the person’s name, and links to his or her social media profile. To protect privacy, it recognizes only those who have agreed to participate. And the app’s creators say it automatically deletes users’ data after an event.

Ann Cavoukian, a privacy expert who runs the Privacy by Design Center of Excellence praises the app’s creators for these protective measures. She cautions, however, that when people choose to share their personal information with the app, they should know that “there may be unintended consequences down the road with that information being used in another context that might come back to bite you”.

The start-up has also developed a version of the app for individuals who suffer from prosopagnosia, or “face blindness”, a condition that prevents people from recognizing individuals they have met. To use this app, a person first acquires an image of someone's face, from either the smartphone’s camera or a photograph, and then tags it with a name. When the camera spots that same face in real life, the previously entered information is displayed. The collected data are stored only on a user's phone, according to the team behind the app.

1.Social Recall is used to_________.

A.identify people B.take photos C.organize events D.make friends

2.Paragraph 3 is mainly about_________.

A.what people can do with the app B.how the app was created

C.what makes the app popular D.how the app works

3.Social Recall helps people with prosopagnosia by ________.

A.giving names to the photos kept in their smartphone

B.showing the person's information when it spots a stored face

C.providing the information of a person when they first meet

D.collecting information previously entered in the phone

4.What can we learn about Social Recall from the passage?

A.It can cure people’s “face blindness”.

B.It has caused unintended consequences.

C.It may put people's privacy at risk.

D.It is praised by users for its protective measures.