1.conveyed的用法是正確的,英語中有三類詞是非謂語動(dòng)詞：不定式,動(dòng)名詞和過去分詞,動(dòng)名詞表主動(dòng),而過去分詞表被動(dòng),在the symbolic meanings subtly conveyed中,主語與動(dòng)詞是被動(dòng)的關(guān)系,那么為什么用非謂語動(dòng)詞呢,很簡單,除了復(fù)合句和幾個(gè)謂語同時(shí)并列的情況,一個(gè)句子只能有一個(gè)謂語動(dòng)詞,后面的 should be taken 就是這句話的謂語,而subtly conveyed 只是作定語修飾前面的主語,同時(shí)這句話我們可以把它改成一個(gè)定語從句：the symbolic meanings which are subtly conveyed should be taken more seriously.這樣應(yīng)該好理解了吧?
2.be to do是不定式作表語,不定式作表語表示具體動(dòng)作或?qū)韯?dòng)作,如：
My work is to clean the room every day.
His dream is to be a doctor.