Abstract
1. Introduction
2. How can comprehensibility be achieved?
2.1. The definitions of input
2.2. The process of comprehension
3. The importance of comprehensible output
4. Interaction for pushing more comprehensible output
4.1 Interaction provides chances for the negotiation of meaning
4.2. Meaning negotiation devices
5. Conclusion: The role of input and interaction
6. Teaching implication
References