Hi Everybody,
I have two sentences which I have misunderstood badly.
1. He has been drinking too much lately. (Can I use present perfect)?)
2. She has read 20 pages so far. (Can I use present perfect progressive?)
Hope you can help me.

The first sentence is usually used Present perfect progressive. You know why? The adverb Lately expressed us that such behavior, I mean his drinking, is behaved temporarily not permanently. He just drinks like this currently or lately but before is not.
The sencond sentence should be general used as Present perfect simple. You know why? Talking about somewhat or entire completed result, Present perfect simple is always used! You see your sentence mentioned about the completed result, 20 pages, accordingly we cant use present perfect progressive in term of grammatical correction use.
That's what I think!

Kimlong