《论语》中有一句话“己欲立而立人,己欲达而达人”,说明人与人之间要理解。理解他人的关键是( )
A:积极倾听
B:学会表达
C:学会换位思考
D:学会打招呼
She didn't know__________she could express her ideas clearly when she was invited to speak at the meeting.