“It is known that Chinese people are smart.” 中的It 指代that Chinese people are smart.it 不是只能指代一個(gè)名詞嗎？SAT作文中讓這么用嗎？it 不只是指代一個(gè)名詞。it可以指代天氣、距離和時(shí)間；it可以做形式主語；it可以做形式賓語。
“It is known that Chinese people are smart.” 中的It作形式主語， 指代that Chinese people are smart這個(gè)真正的主語。