Mainly because I know how harsh these sort of terrains can be.

疑问语序：How harsh can these sort of terrians be？

陈述语序：How harsh these sort of terrians can be？

这里的How harsh是做表语吗？

疑问语序：How happy can we be friend？

陈述语序：How happy we can be friend？

这里的How是做状语吗？