单选题
According to the passage, compared to 3G mobile phones, the second-generation phones ______.
A、
do not receive signals transmitted with an electromagnetic field
B、
can receive signals from a larger area than 3G mobile phone
C、
cause worse impact when they are used close to the head
D、
have no negative impact on human health
【正确答案】
D
【答案解析】
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