请问 Where are/is my computer and book?

are

There be句式中若有几个并列成分充当主语时,谓语动词的形式由第一个并列成分决定。如:

There is an apple and some oranges on the table.

There are some oranges and an apple on the table.

is 因为后面跟的computer是单数

is,就近原则

答案仅供参考