Here's why:
* Helping verbs help the main verb in a sentence. They are used to form different tenses, moods, and voices. Common helping verbs include *be*, *have*, *do*, *will*, *can*, *could*, *may*, *might*, *should*, and *would*.
* "Delicious" is an adjective that describes the cake. It modifies the noun "cake" and tells us what kind of cake it is.
The structure of the sentence is:
* Subject: The cake
* Verb: looked
* Predicate adjective: delicious
In this case, "looked" is the main verb, and "delicious" modifies the subject ("the cake") to provide more information about it.