题干
We should never give up ___________ others. Sometimes helping others means helping ourselves.
A：to help
B：helping
C：helped
D：help
答案(点此获取答案解析）
B
We should never give up ___________ others. Sometimes helping others means helping ourselves.
A：to help
B：helping
C：helped
D：help
，则它们之间的为库仑力将