The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.
A. to be invented B. having been invented
C. invented D. to have been invented
The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.
A. to be invented B. having been invented
C. invented D. to have been invented
D
本句考查动词的被动语态和时态，it+is+动词ed形式，to do是固定的搭配用法。而Bunsen Burner的发明是过去发生的动作，所以用完成时态。