1-He Had Scarcely Crossed The Road Before The Bus Came.
2-They Had Hardly Reached Their Shelter When It rained.
-Can We use 'Before' And 'When' Interchangeably in these sentences?
1-He Had Scarcely Crossed The Road Before The Bus Came.
2-They Had Hardly Reached Their Shelter When It rained.
-Can We use 'Before' And 'When' Interchangeably in these sentences?
I suppose when we want to emphasize 'scarcely' or 'hardly', 'when' is more appropriate than 'before'. If we don't, the grammar is always correct but the meaning is a little different due to differences between 'when' and 'before'.
Because when we talking about 'scarcely', we prefer to mean that the 'cross' action was finished just a little bit earlier(e.g., a few seconds, it's a qualitative description.) than the timing when bus arrived. This just matches the meaning of 'when'.
You can use either, but the past perfect usually involves a moment of time, which serves as something of a reference point, a landmark to compare against—it situates an event as having taken place earlier than that moment. Thus, “I had scarcely awoken before my alarm sounded” sounds, to my ears anyway, a trifle… off.
Think of the past perfect along these lines:
I slept fairly late.
Was it your alarm that woke you?
No, though when it rang at 9:00 on the dot, I had scarcely awoken.
(In that example, the reference moment 9:00 sharp.)