908 B
General Information:
Here Isaiah describes events that will happen in the future as if they happened in the past. This emphasizes that they certainly will happen. (See: rc://en/ta/man/translate/figs-pastforfuture) Isaiah continues describing Yahweh's servant.
Who has believed what they heard from us
What Isaiah just found out is so amazing that he wonders if the exiles will believe it. The "we" includes him and those in exile. AT: "It is hard for anyone to believe what we have heard" (See: rc://en/ta/man/translate/figs-inclusive and rc://en/ta/man/translate/figs-rquestion)
to whom has the arm of Yahweh been revealed?
Arm refers to God's power. This can be stated in active form. AT: "Yahweh has revealed his power to people." (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-activepassive and rc://en/ta/man/translate/figs-rquestion)