Question

動詞的分類：行為/實義動詞、及物與不及物動詞、瞬時與持續動詞、狀態與動作動詞、 助動詞、情態動詞與連系動詞

1. There is someone knocking at/on the door. Who ________ it be?

  A) may            B) will            C) can          D) must

Answer 1

C