He ..... (fall) while he ..... (climb) the ladder.
He fell while he was climbing the ladder
She ..... (fall) asleep while she .... (knit)
She fell asleep while she was knitting.
When she ..... (cook), she .... (burn) herself.
She was cooking, she burned herself.
She .... (hurt) her back when she .... (lift) the box.
She hurt her back when she was lifting the box.
He .... (play) tennis when a tiger .... (attack) him.
He was playing tennis when a tiger attacked him.
When she .... (arrive), they .... (watch) TV.
When she arrived, they were watching TV.
He ... (swim) when the plane .... (crash).
He was swimming when the plane crashed.
