Sentence 1: He and his schoolteacher wife, Linda, probably didn't know they were starting out on the poor side.

Sentence 2: His wife, Linda, was a doctor.
Is this second sentence entailed by the first?

Answer: no

Sentence 1: Many of these modes of communication are very attractive alternatives to traditional postal delivery services supplied by the United States Postal Service (USPS).

Sentence 2: The many modes of communication are very attractive alternatives.
Is this second sentence entailed by the first?

Answer: yes

Sentence 1: (Yes, if it uses speed attacks rather than electrical ones.)

Sentence 2: Speed attacks are better to use than electrical ones.
Is this second sentence entailed by the first?

Answer:
it is not possible to tell