In sentence 1, I would prefer using past continuous (he was holding the hand ...), because using past simple will make it sounds like he held some white girl's hand habitually. (Note: If you change because to after, I think held will be more appropriate. It should also be even more appropriate than past perfect, in my opinion.)
To explain why using past continuous (or past progressive) is preferred, here is the closest entry I can find in Practical English Usage by Michael Swan.
422 past (2): past progressive (I was working etc)
3 past progressive and simple past: 'background' events
We often use the past progressive together with a simple past tense. The past progressive refers to a longer 'background' action or situation; the simple past refers to a shorter action or event that happened in the middle of the longer action, or that interrupted it.
As I was walking down the road, I saw Bill.
The phone rang while I was having dinner.
Mozart died while he was composing the Requiem.
In sentence 2, if you have this sentence alone:
Fans (queued/were queuing) overnight at a Hollywood music shop for the chance to get Lady Gaga's autograph.
I would say that either queued or were queuing can be used, depending on the way you want to narrate the scene. If you were a journalist writing it as a news, I think using queued would be more appropriate. However, if you were an anchor reporting the news, using were queuing would be more appropriate. This is because, according to my observation, TV news anchors usually use progressive tenses to arouse our attention, to make us feel as if we were in the scene of the news they are reporting.
However, when you gave the full passage,
Fans (queued/were queuing) overnight at a Hollywood music shop for the chance to get Lady Gaga's autograph. While they were waiting, Gaga saw their tweets. She immediately ordered 80 takeaway pizzas and sent them to her fans in case they were hungry.
I changed my preference to queued immediately. The reason is because it will provide the background (or the first reference time [ref.], if you prefer) for the whole story. Besides, there is already one use of the past progressive (... they were waiting, ...) as the main event of the whole story, which is sufficient for a news report.
Both sentences are correct.
I had been training for years before I could do that jump
To my ear and brain, the focus in the sentence is on the time it took to train for the jump.
I had been training for years when I finally did that jump
Whereas in this sentence, it is more on the event of finally performing the jump.
Best Answer
Past perfect continuous tense indicates something habitual or progressive that occurred in the past: "I drank tea because I had been running out of coffee" puts the coffee shortage further in the past relative to the drinking of tea, and means that you were, but are no longer running out of coffee, which implies you have enough coffee now (at the point of time of drinking tea) -- so why is that a reason to drink tea? That makes your sentence illogical from a strict semantic perspective, though your listener will understand your meaning anyway. So the more grammatically appropriate statement would be either
or
as the test corrected you.
You can even informally use simple past tense as in "I had a cup of tea because I ran out of coffee" but past perfect is the formally correct option.
Paradoxically, past perfect continuous works if you say it first, as in
This sentence is correct because the construction puts the process of running out of coffee in the past relative to the point in time of making the statement. Equally correct: