Itis+nouse,nogood(fun,agreatpleasure,awasteoftime,abore...)等名词+doingsth.
Itisnousecrying.哭没有用.Itisnogoodobjecting.反对也没有用.
Itisagreatfunplayingfootball.打篮球很有趣.
Itisawasteoftimetryingtoexplain.设法解释是浪费时间.
Itis+useless(nice,good,interesting,expensive等形容词)+doingsth.
Itisuselessspeaking.光说没用.
Itisniceseeingyouagain.真高兴又遇到了你.
Itisgoodplayingchessaftersupper.晚饭后弈棋挺好.
Itisexpensiverunningthiscar.开这种小车是浪费.