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What do you use to unlock your cellphone？ A password？ A fingerprint？ Or simply a glance（一瞥）？

On September 12， 2017， Apple introduced its iPhone X， which has an eye﹣catching feature （特色）﹣Face ID．

With Face ID， Apple says， you can unlock your new iPhone by just looking atit． It is powered by a so﹣called TrueDepth camera system built into the front of the iPhone X．

When the camera system sees a person's face， it uses 30，000 unseen dots （点） to "'map"（勾画）the shape and outline of the face． A mathematical model of the face will then be created and stored （储存） in the phone．

The next time the person looks at the iPhone X， the same dots are mapped onto his or her face and compared to the stored model． If the two match， then the phone unlocks．

This happens in less than a second．

Apple says the system is smart． If you change your hairstyle， put on sunglasses or makeup， or use the phone in the dark， Face ID still works．

Although the technology sounds fancy， there are still concerns （担心）． For example，will Face ID work for twins？

According to Apple， the chance of others to unlock your iPhone X using Face ID is one in a million． Face ID can tell the difference between twins， but the error rating （出错率） rises． So one would need to set a password then．

Apple also emphasizes （强调） that Face ID only unlocks when you stare atit． It is what Apple calls"attention aware （察觉）"． So the phone won't unlock if you are just glancing at the phone for the time． It won't work either if someone puts the phone at your sleeping face or your photo．

（1）The new function （功能） of the iPhone X is that you can unlock it with 　　．

A．	a sign	B．
C．	a password	D．
E．	a fingerprint	F．
G．	Face I	H．

（2）The camera system of Face ID works by 　　．

A．	remembering users' faces by taking their pictures
B．	using a map to store face models of its users for later use
C．	matching the users' faces with unseen dots stored in the system
D．	creating a face model of the user and comparing it with the user's face later

（3）Face ID doesn't work when you 　　．

A．	wear a mask
B．	put on sunglasses
C．	change your hairstyle
D．	use the iPhone X in the dark

（4）You would need to set a password to prevent 　　to unlock your iPhone X with Face ID．

A．	your parents
B．	your classmates
C．	your twin brother
D．	your best friend

（5）The main idea of the passage is that 　　．

A．	the iPhone X can't recognize a person's face
B．	Face ID is a program to unlock the iPhone X
C．	people worry about the safety of using Face ID
D．	we can unlock the iPhone X in three different ways