this an egg is for you,这句话对吗?要不要加冠词an,为什么?

Is this an egg? 这句话为什么没有加冠词an.Lucy is our office assistant. is this an apple an orange__an egg The big ( )(橘子）are for you.括号里填什么?This is an egg.改为否定句.（ ） （ This building is an university.这句话的冠词应该怎么改才是对的? 来看哈我这句话要不要加冠词! 英语中形容词前加冠词,形容词后接名词对吗?She is an Fench student. This is an egg (改为复数形式） this is an orange.it is orange.为什么第一个加an,而第二个不加an An Easter egg hunt is a game for ___________. I am convinced that she is honest girl.这句话算有语病吗?是否应该加冠词an? He is an egg on his head now.要加动词put,该怎样填