Question

— What are the _______ doing there?
— They are busy _______ their science experiment.

A．Boys students; to do	B．Boy students; to do
C．Boys students; doing	D．Boy students; doing

Answer 1

D

考查名词复数和非谓语动词的用法。男学生的复数表示为boy students，固定结构“be busy doing sth”忙于做某事。