Sentence 1: Most folks have a pretty clear idea of how much pleasure they'll get from their brother's smiles or a few days of sand and surf.

Sentence 2: No one has an idea of how good it will feel to get a smile from their sibling.
Is this second sentence entailed by the first?

Answer: no

Sentence 1: If you are convinced he did it," said Poirot quietly.

Sentence 2: He might have done it.
Is this second sentence entailed by the first?

Answer: yes

Sentence 1: Oh, hurry! They were now at the corner of Carlton House Terrace, and their spirits lightened.

Sentence 2: They had just arrived at the corner of Carlton House Terrace
Is this second sentence entailed by the first?

Answer:
yes