These main cables form a parabola
A cable hanging under its own weight forms a catenary, not a parabola. I presume that still applies when you hang a roadway from it.
more than twice as popular
... as all other operating systems combined
That's just a dramatic way of saying “>67% market share.”
Not only were rockets working, they had been in practical use for centuries.
Maybe this would be correct if we said “outer space rockets” specifically. The principles were pretty well understood, but we couldn't yet build one.
Sustainable fusion reactions aren't quite reality yet.
1. A robot may not injure a human being or, through inaction, allow a human being to come to harm.
2. A robot must obey the orders given it by human beings, except where such orders would conflict with the First Law.
3. A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.
Machines certainly can solve problems, store information, correlate, and play games -- but not with pleasure. -- Leo Rosten