the book are on the bookcase .改为否定句 the baseball is under the bed.改为一般疑问句

原句 ：The books are on (aren't) the bookcase .
否定句 ：The books are not (aren't) on the bookcase
原句 ：The baseball is under the bed.
一般疑问句 ：Is the baseball is under the bed

The book aren't on the bookcase .
Is the baseball under the bed.
楼主你几岁呀？

the books aren't on the bookcase.
is the baseball under the bed.

the book are not on the bookcase 。 该否定句，有be动词的，在后面加not 就可以了
Is the baseball under the bed？ 含be动词的疑问句，一般把be动词调到句首就可以了。

1.原句 ：The books are on (aren't) the bookcase .
否定句 ：The books are not (aren't) on the bookcase .
(我觉得你题目上的单词" book" 应该是单词"books" ,因为你在后面用了"are"一词.而单词"are"是一个用于复数形式的单词）
2.原句 ：The baseball is under the bed.
一般疑问句 ：Is the baseball is under the bed .