Teacher: Given a disfluent sentence, modify the sentence to it to its equivalent fluent form, preserving the meaning of the sentence.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Who did the Han Chinese want to help the Khitan no I mean the Mongols fight?
Solution: Who did the Han Chinese want to help the Mongols fight?
Reason: The input initially means Khitan and then changes to Mongols, hence this is correct.

Now, solve this instance: What was the most important discovery that led to the intimate coupling no the understanding that Earth's lithosphere is separated into tectonic plates?
Student:
What was the most important discovery that led to the understanding that Earth's lithosphere is separated into tectonic plates?