题目

Mother bought many tomatoes from the market two days ago, ________ some have gone bad due to the bad weather. A . of those B . from which C . of which D . in which 答案：C如图所示，直线a、b和c、d是处于匀强电场中的两组平行线，M、N、P、Q是它们的交点，四点处的电势分别为、、、。一电子由M点分别运动到N和P点的过程中，电场力所做的负功相等。则A．直线a们于某一等势面内，B．直线c位于某一等势面内，C．若电子由M点运动到Q点，电场力做正功D．若电子由P点运动到Q点，电场力做负功