Terminology varies a little from country to country and ven from grammarian to grammarian. My opinion:
Anonymous“Are gerunds verbs?”
No, but a gerund can take an object and may occur in the passive voice like a verb. I consider a gerund neither a verb nor a noun but a little bit of both.
Anonymous “are infinitives verbs?”
Yes.
Anonymous “' She is swimming' are both 'is' and 'swimming' the verb or only 'is'?”
Both are verbs. Swimming is a present participle.
Anonymous “'That could be fun' are the verbs 'could' and 'be', or just 'be'?”
Both a verbs. Could is a defective auxiliary (also known as a modal auxiliary) and be is a present infinitive. All infinitives are verb forms.
Anonymous “Can you have multiple verbs running consecutively in a sentence?”
No problem. He would have liked to speak Japanese.
The underlined words are verbs. Would is a defective auxiliary [verb], have is an auxilary used to form the perfect infinitive have liked. Liked itself is a past participle. To speak is a complete present infinitive. 'Complete' means that it is complete with to, which is omitted in some cases. Here's one of them: He can speak Japanese.
CB