Hard to recur once.是什么意思?

Hard to recur once. Hard to recur once.是什么意思? Many things once miss is hard to Will you remember many years later there once waa boy who tried hard to cherish you If I leave,can you trying hard to think that I once 是hard to do sth 还是 hard doing sth ONCE（一旦）引导的是什么状语从句?Once you get into a bad habit,it will be very hard to get rid of it.你一旦染上坏习惯,就很难摆脱.请问这个once从句到底是时间从句还是条件从句?我弄糊涂了. Once again choose to ignore,Once again choose to believe you.believe you.中文是? ----Look!She is sking so fast!----Hard to ( ) her legs were once broken.A:know B :realize C :im----Look!She is sking so fast!----Hard to ( ) her legs were once broken.A:know B :realize C :imagine D:find _Look!She skiing so fast!-Hard to()her legs were once broken.A know B realize C imagine D find It is said that the old man___company I once worked for more than 10 years is friendly to usemployees but very hard on his own family.答案是for whose 还是 whose? 英语神人 请帮我看下句子 是关于英语语法的~The possibility that mass extinctions may recur periodically has given rise to such hypotheses as that of a companion star with a long-period orbit deflecting other bodies from their normal 是i find it hard to say 还是i find it is hard to say 难以想象是find it hard to imagine 还是hard to imagine? it's hard to navigate.中的to navigate是动词不定式吗?hard是什么成分? 呼吸困难的英语是hard to breath还是hard to breathe? hard可以表示严格吗?如果可以,是用be hard to sb.还是be hard on sb.? jim s_____ chinese very hard lt's s_____ today.let's take him to the hospital at oncejim s_____ chinese very hard是一句lt's s_____ today.let's take him to the hospital at once是一句