题目

I’m considering _______ a washing machine, which is considered _______ a great help to my wife. A. buying; to be                    B. buying; being C. to buy; being                    D. to buy; to be 答案：A在匀强电场中只受电场力而做曲线运动的质子，单位时间内速度的改变量总是（ ）A．大小相等，方向相同B．大小不等，方向不同C．大小相等，方向不同D．大小不等，方向相同