It\'s your turn to be on duty这个句子中的动词不定式起什么作用?

It\'s your turn to be on duty这个句子中的动词不定式起什么作用? it's your turn to be on duty 不定式在句中做什么成分 It’s your turn to be on duty._______ it is your turn to be on duty.（ ） It's your turn to be on duty（） A、so it is B、so am I it is your turn to be on duty ,为什么用so it is,而不用so i am l'm at school and it's my turn to be on duty today的意思是什么 几个动词不定式的问题It was supposed to be turned in on Friday.中的不定式为何是 连词成句 turn it to is duty on my today be it's your turn to do a duty report（改为同义句） 英语翻译1.Today I am on duty,it's my turn to clean the classroom whose turn is it-------（be） on duty today