21._____by a desire to learn, he was not interested in children’s play and adventure when he was young.

A．Driven

B．Driving

C．To drive

D．To be drive

以下物质间的每步转化通过一步反应能实现的是[ ]

①Al→Al₂O₃→Al(OH)₃

②Fe→FeCl₂→Fe(OH)₂

③S→SO₃→H₂SO₄

④N₂→NO→NO₂

A．①②

B．③④

C．②④

D．①③