The first gap is best filled with "resembled" (Sebastian comments here that many people believed that his sister was similar to him in the looks)
The second gap is "remembrance" - he means here that he cries after her (the more refers to more salt water, that is his tears)
Happy medium doesen't want to get too attached to people the happy medium does not want to be bothered
Answer:
D. Sai thinking about her first science experiment
