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

Since then, the Great Wall of China __________________ a symbol of wisdom and bravery of the Chinese people and a monument to Chinese nation for many hundreds of years.