处在如图所示的四种电场中P点的带电粒子，由静止释放后只受电场力作用，其加速度一定增大的是：（ ）
A：
B：
C：
D：
——Will you join us to play basketball on Saturday afternoon?
——________, but I promised to go swimming with Eric.
A lack of________of cultural difference to local customs can cause problems.
