把宾语从句拿出来：
what are most delicious are the cakes in that shop.
what are most delicious这是宾语从句中的主语从句.
用are是因为后面是cakes
这也有人说是系表一致,也就是谓语的单复数根据表语决定.
如：
What he wants to buy are some books.
What he wants to buy is a book.
what 引导的宾语从句,动词单复数问题
把宾语从句拿出来：
what are most delicious are the cakes in that shop.
what are most delicious这是宾语从句中的主语从句.
用are是因为后面是cakes
这也有人说是系表一致,也就是谓语的单复数根据表语决定.
如：
What he wants to buy are some books.
What he wants to buy is a book.