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问题 选择题

下列有关元素的叙述正确的是（　　）

A．金属元素与非金属元素之间能形成共价化合物

B．只有在原子中，质子数才与核外电子数相等

C．不同种原子之间形成的共价键一定是极性共价键

D．目前使用的元素周期表中，最长的周期含有36种元素

答案

答案：A

选择题

赤道与本初子午线相比，正确的说法是（　　）

A．赤道与本初子午线长度相等

B．赤道比本初子午线长度短

C．本初子午线是赤道长度的两倍

D．赤道长度是本初子午线的两倍
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单项选择题

Many people are wondering if it is safe to talk on the phone while driving. There have been quite a few accidents while drivers were talking on the phone. Some research is being done to find out if driving while talking on the phone is dangerous.
When there is a car accident police officers will find out if any of the drivers were using a cell phone. They will write this information in a report. The information will be saved and later studied.
There have been some very bad car accidents caused by drivers being distracted by cell phones. Drivers sometimes forget to watch the road carefully when they are using their phones. Not paying attention to the road can be dangerous, even deadly.
It is important for drivers to focus on the road. They need to pay attention to what is going on around them. They might need to stop or swerve quickly.
People want to make sure that the roads are safe for everyone. Studies will be done using the information police officers collect at accidents. Maybe someday this information will lead to laws about driving and using cell phones.

Driving and talking on the phone at the same time could be______, research says.

A．difficult

B．dangerous

C．illegal

D．fun
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