Answer:
The gerund or gerund phrase in the sentences above are the following ones: racing (1), collecting coins (2), digging in the garden (3), hooking the cars together (4), and exercising dailly (5).
Step-by-step explanation:
Gerunds are words that are formed with verbs but act as nouns. Thefore, they can act as subjects, objects of prepositions, or subject complements. In this case, the gerund is acting as a subject in sentences 1, 2, 5. Then, the gerund phrases act differently. The one in sentence 3 acts as subject complement and 4 as the object of the preposition by.
The difference between a gerund and a gerund phrase is that the latter has objects (complements or modifiers that act together to behave as a noun).