1 Seeing is believing./ Cf. To see is to believe.眼见为实( 对称原则)
2 * It is no use/ no good/ useless doing 做…(没)有用
It is a waste of time (/worthwhile) doing sth.做…是浪费时间/ 是值得的（注意是It is 开头）
区别 It is important/ necessary/ essential/ possible… to do sth.
3 There is no sense/no point/no harm (in) doing sth.做..没有意义/ 做…没有坏处
区别 There is no need to do sth 没必要做… （注意是There is 开头）
