物体在两个力的作用下保持平衡的条件是：这两个力的大小（）方向（），且作用在（）上。
参考答案：相等、相反、同一直线
After ________ my room, I with Li Lei and Li Xiang ________ to an aquarium. [ ]
A. finished doing, go
B. finishing cleaning, went
C. finished cleaning, went
D. finishing cleaning, go
