题目

 Almost all theme park accidents can be prevented. Here, based on coverage of theme park safety, are some tips to help you and your family stay safe on your next visit. If you are visiting with a child, take a moment to explain the ride to them, and tell them how they should behave. They are depending upon you to keep them safe. Set a good example for them by following the rules of the park, and make sure that they know you expect them to follow those rules, too. Tell them to stay seated, to hold the grab bar or put their hands in the laps, and not to stick their knees and feet outsi图1-4-1所示是某电场中的一条直电场线，一电子从a点由静止释放，它将沿直线向b点运动.下列有关该电场情况的判断正确的是（    ） 图1-4-1A．该电场一定是匀强电场                                   B．场强Ea一定小于EbC．电子具有的电势能Epa一定大于Epb                  D．电势φa一定低于φb