Using your smartphone might be fun，but be careful too much screen time may be harmful to your health.First，it's bad for your（1）

A

A

.A researcher called SarahHinkley says the problem comes from the blue light that the screen（2）

C

C

.Looking at a smartphone for a long time can cause eye strain（勞損），headaches and dry eyes.So you'd better take a break every 15 minutes when you are working at a computer or using a smartphone.
   Second，screen use can do harm to children's brains.A new study（3）

B

B

that using screens too much can affect how children's brains grow.If children use screens for（4）

D

D

than one hour a day，they might have lower levels of white matter in their brains.White matter is a key（5）

B

B

the development of language and reading skills.（6）

C

C

it is wise to cut down the time of children using all kinds of screens.
   Third，using screens（7）

D

D

will affect your sleep.According to a study，about 95% of the people between the ages of 13 and 64 use electronics before bed，especially the young people under 20.Doctors say that the light from those electronics at night may make you excited before you go to bed.Then it's（8）

B

B

for you to get enough sleep.So you 'd better（9）

C

C

smartphones，TVs，and all other screens an hour before you go to bed.To keep healthy，doctors and researchers strongly advise that you（10）

D

D

use screens for long hours.

（1）	A．eyes	B．brains	C．head	D．ears
（2）	A．gives away	B．gives in	C．gives out	D．gives up
（3）	A．teaches	B．shows	C．calls	D．works
（4）	A．less	B．higher	C．fewer	D．more
（5）	A．of	B．to	C．in	D．for
（6）	A．If	B．But	C．So	D．When
（7）	A．too many	B．too little	C．much too	D．too much
（8）	A．easy	B．difficult	C．relaxing	D．possible
（9）	A．turn up	B．turn down	C．turn off	D．turn on
（10）	A．can	B．should	C．need	D．shouldn't