What it means is that he wouldn't have been able to get where he got if it hadn't been for the scientific achievements of his predecessors. If it hadn't been for these "giants" that enabled him to see so far, he wouldn't have been able to make all the discoveries that he did. For those coming after him, he was a giant that enabled them, and so laws and theories and scientific knowledge always increases based on the knowledge before it.
Answer:
Jack is going hiking in the mountains and wants to borrow my boots, but I'm not sure they will fit him.
Explanation:
Here! The ones that are crossed are answers as well just look for the place of the letter for them. I hope I could help. Have a great day :)
