Sentence 1: It is impossible for him to be present in person." He stopped, giving a curious impression of having left the sentence unfinished.

Sentence 2: He can be present in person.
Is this second sentence entailed by the first?

Answer: no

Sentence 1: Or did they arrive after an earlier migration or settlement of Indo-Europeans from Central Asia, or early Europeans?

Sentence 2: They arrived 100 years after the migration of either the Indo-Europeans or early Europeans.
Is this second sentence entailed by the first?

Answer: it is not possible to tell

Sentence 1: According to the Maastricht Treaty, the currency will be put into circulation only after individual national economies have hit certain targets--such as a sufficiently low ratio of debt to gross domestic product.

Sentence 2: There is currency that has not yet started to circulate.
Is this second sentence entailed by the first?

Answer:
yes