Пунктуация английского языка

At the end of a declarative sentence — one-member or two-member — a full-stop (a period or a dot) is placed to denote fall of tone, completeness of the thought, and a pause.
The voice dropped to a whisper. [G.] He swung round and walked down the road. [Cr. ]
Three hundred pounds.[Sn.]
The same in Russian.