Hello all you people who suck

Which sentence you is an example of chronological structure in “the city without us”?

The reversalists continue their labors, confident that they will one day construct an engine that generates more compression than it uses, a perpetual power source that will restore to the universe its lost vigor. which theme is best supported by the excerpt? a. scientific study requires dedication and perseverance. b. people will always look for a way to achieve immortality. c. death must always be endured alone. d. change is difficult to accept but beneficial if embraced.

1. in which sentence is the underlined portion a predicate nominative? for astronauts, going into space to repair orbiting equipment becomes a challenge. for astronauts, going into space to repair orbiting equipment becomes tricky. for astronauts, going into space to repair orbiting equipment becomes challenging. for astronauts, going into space to repair orbiting equipment becomes frequent.