Be nice to your friends when you are at school.是省略句吗?主句为什么没有

Be nice to your friends when you are at school.是省略句吗?主句为什么没有 翻译：be nice to your friends when you are at school. 英语翻译When you are in trouble at school,your friends will help you must ( ) youself to be more at your ease when you are wi when you are at your school,where is east? what are you going to be when you ()(leave) school When are your friends returning to Italy? to be at work when you are sick是什么 连词组句；to,nice,see,you,again good,are,we,friends At school there are strict rules————.为什么是to be kept you are very nice to be my friend的意思 TO BE 为什么用这里 be nice to friends是什么意思