What are the three kinds of learning and teaching materials in use by teachers adopting the Communicative Approach?

What are the three kinds of learning and teaching materials in use by teachers adopting the Communicative Approach?

They are text-based materials, task-based materials and realia.
全题共5分,答案含三点,第一、二点每点2分、第三点1分。如答案要点不完整,酌情扣分。如表述有语法、拼写、标点等问题,也酌情扣分,但全题在这方面的扣分不得超过1分。