Question

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Answer 1

1) Had been cycling, stopped.
2) Had been walking, found.
3) Had been waiting, arrived.
4) Felt, had been digging.
5) Prepared, had been cooking.
6) Had been snowing, changed.
7) Had been surfing, found.
8) Had been conducting,
9) Wondered, had been waiting.
10) Had been staring, understood.

Объяснение: То действие, которое произошло раньше второго, ставится в Past Perfect (Continuous). Соответственно, действие, произошедшее позднее, ставится в Past Simple.