The Relative Clause is “who are five in number”. It is a type of dependant clause (it need the main clause in order to convey its meaning properly) that has the same function of an adjective; that is to say, it modifies a noun “friends”.
Answer:
<h2>Slowly is the adverb, crawled is the verb.</h2>
An abandoned office would most likely be the best one. Just by hearing the word abandoned, it can give people chills because they don't expect what that abandoned office have. In a fiction story, it might have zombies or something.