_________ means a computer that is portable and suitable for use while traveling.
A. laptop
B. converter
C. hard drive
D. digital TV
面积归一法属于哪种杂质检查方法（）
A. 薄层色谱法
B. 光谱法
C. 高效液相色谱法
D. 化学法
In which aspects has your life been affected by digital products?
A. pay the bill
B. order food
C. shopping online
D. A, B and C
What is the weakness of smart phones?
A. It can lead to impared eyesight
B. search for information
C. surf the Internet
D. communicate with friends
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