When I finished the story, Lenin jumped up from his chair and started pacing the floor, ______, deep in thought.

A．with his head bending

B．in his head bent

C．his head bending

D．his head bent

在Fe₂(SO₄)₃、CuSO₄、Al₂(SO₄)₃的混合溶液中通入适量H₂S，产生的沉淀物是

A．FeS和CuS

B．CuS

C．CuS和S

D．Al₂S₃、FeS和CuS