It has long been ....(?)... That small downturns in the US Economy can have a global impact. Mohon bantuannya beserta alasan dari jawaban

It has long been knowing that small downturns in the US Economy can have a global impact .
=> "Telah lama diketahui bahwa kemerosotan kecil pada ekonomi taksi di US mempunyai dampak global"

Rumus simple perfect continuous :
=> S + has/have + been + Verb-ing

semoga membantu ^_^