Given a sentence, identify the verb phrase.
John had been running for six hours.
The verb phrase in the sentence "John had been running for six hours." is "had been running".
Complete the following task based on the instruction and optional input provided.### Instruction:
Given a sentence, identify the verb phrase.

### Input:
John had been running for six hours.

### Output:
The verb phrase in the sentence "John had been running for six hours." is "had been running".