Jaký čas má být použit? (Angličtina a past simple and continuous)

Dobrý den, chtěla bych se zeptat jaké časy mají být v následujících souvětích:
1, We were crossing a bridge when we met ani elephant NEBO We crossed a bridge when we were meeting elephant?
2, We were having a picnic when a horse ate our food NEBO we had a picnic when a horse was eatting our food?
3, We were cycling trought the town when started a rain NEBO we cycled trought the town when rain was startting?
4, Helen was sending a message when dropped her phone in to the river NEBO Hellen sent a message when she dropping her phone in to the river?
5, Jeremy was taking a photograph when ball hit him NEBO Jeremy took a photograph when ball was hit him?

Je to důležité a žádám o pomoc. Omlouvám se za některé chyby v textu.