1 and 1-1 are understandable, but the wording is not quite right (and in 1-1 the word "for" means that their captors intended them to freeze). They should be something like: The prisoners were transported to Siberia, and many were to suffer severely from the sub-zero temperatures. The adverb "extremely" is not be used like you used it.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.