Apparently it never occurs to them that you can't make rapid, drastic changes in the technology and the economy of a society without causing rapid changes in all other aspects of the society as well,.
The chemical monofluoroacetate occurs in all parts of Dichapetalum cymosum, and is responsible for its toxic effects.
The liftoff will occur in exactly twelve seconds.
I will write if the opportunity occurs.
... sooner than it would otherwise occur. ...
... So mistakes do occur. ...