Bonjour

a- Gold diggers had tried their luck in North Carolina but not in California si far.

b- Most newcomers had never experienced gold prospecting before.

c- They hadn't thought of staying in California but were obliged to.

d- The train had just left when they had arrived at the station.

Pour la dernière phrase il serait logique de mettre le second verbe au prétérit puisqu'il y a 2 actions, l'une étant antérieure à l'autre. =>

The train had just left when they arrived at the station.

.....mais comme il est demandé de tout mettre au past perfect...

Tu pourras demander au prof. D'un point de vue grammatical, ce serait mieux...

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Bonne journée

judith57 Merci beaucoup pour votre aide.
Bonne journée

nathea avec plaisir :)