this is an apple 和 this is apple 哪个语法是正确的

this is an apple 和 this is apple 哪个语法是正确的 This is an red apple.写出正确的句子 ls this an apple?的肯定回答是Yes,this is an apple.还是Yes,it is an a is this an apple an orange__an egg This is an apple就an apple部分转换提问 this is an apple.改成复数形式 an,is,apple,this连词成句 This is an apple 变为复数句子 This is ________(apple) This is an apple in English.的答句是什么 This is (an apple)打括号的地方提问 this is an apple的an为什么不可以是a