I came across a website that says using a past perfect continuous is a good way to show cause and effect. The writer then shows an example.
- He was tired because he had been exercising so hard.
But later on he said using a past perfect continuous could cause an ambiguity. He gives an example—that was almost the same as the first sentence.
- Jason was tired because he had been jogging.
He says the sentence could either mean Jason was still jogging at the moment, or that he had finished.
Here's my question: if using a past present continuous to show cause and effect could lead to ambiguity, why not use a past perfect instead if you want to show the action is completed? And past continuous to show the action is still ongoing?
He was tired because he had exercised so hard.
Jason was tired because he had jogged.
He was tired because he was exercising so hard.