This is scissors对吗?

This is scissors对吗? This is a scissors in English是什么意思 Whose is this book ?对吗? This is [you] apple对吗 He bought some scissors for cutting yesterday.这个句子对吗 This is my parents.这句话对吗? Is this boy'cap?这句话对吗 this is a clothes对吗急 this watermelon is big 语法对吗 this is monkey,这样说对吗 this book is my friend's对吗 This is according to...这种用法对吗? this rule is short 这么说对吗 he is here this month对吗 This is a oeange pen对吗? 我写的对吗?Is this your a book?Is this red?我写的对吗? this is pen 对吗This is book.这句话的句式对吗? this is 后加a pen 还是pen ,为什么this is paper可以不加?these are scissors可以不加?请说明一下冠词应在什么情况下加吧,