1)strings problem,绳子问题2)soft-rope query,软绳问题3)problem of norm,准绳问题4)sub-subproblem,子子问题5)the problem of tugging a boat to shore by a string,绳拉船靠岸问题6)control question test,准绳问题测试法
用法和例句
A theorem on kinetic energy for variable mass-point and formula of work of recoil internal forces are given and the reason of soft-rope query is discussed.