to fall is infinite verb.
No sentence has been provided but 'careered' is always a verb.
Diving is the present participle of the verb dive.
"Say" is a verb.
"It" is always a pronoun, unless within quotation marks.
Adjective, and it will always be one.
An adverb.
In the sentence "What can you do," the word "do" is a verb. It is used to indicate an action or something that can be done.
Careful is an adjective.
conjunction
In the sentence "your cousin is always a welcome visitor," the word "welcome" is being used as an adjective to describe the type of visitor your cousin is.
Bolt can be a noun, since a bolt is a type of locking mechanism. Bolt can also be a verb, like in the sentence, "Be careful, or your horse might bolt."
The word information can be used as a noun or an adjective. In the following sentence, it is used as a noun: We acquired the information through careful detective work. In the following sentence, it is used as an adjective: We live in an information society.