To be a good teacher, you need some of the gifts of a good actor: you must be able to【C1】_
A good teacher【C18】______in quite a different way. His students take an active part in his【C19】______: they ask and answer questions; they obey orders; and if they don't understand something, they will say so. The teacher therefore has to suit his act to the needs of his students. He cannot learn his part by heart, but must【C20】______it as he goes along.
【C1】
A.pay
B.hold
C.give
D.know