Пре­об­ра­зуй­те, если это не­об­хо­ди­мо, слово BE так, чтобы оно грам­ма­ти­че­ски со­от­вет­ство­ва­ло со­дер­жа­нию тек­ста.

In countries which are located near sea coasts, sea food is an important part of national cuisine. Since ancient times, different kinds of fish and seafood __________________ staple diets near the coast or near certain rivers and lakes.