The roads were covered in ice; hence it was not safe to drive.
The customer was displeased with her meal, hence the chef prepared a replacement.
Hence the Mediterranean region is characteristically one of winter rains, the distinctive feature becoming less sharply defined from south to north, and the amount of total annual fall increasing in the same direction.
Any portion of the underground rhizome when broken off is capable of producing a new plant; hence the difficulty of eradicating them when once established.
ALF, from 1986 to 1990, featured a puppetry alien (or Alien Life Form, hence the acroynm), and from 1996 to 2001, 3rd Rock From the Sun featured a group of extra-terrestrials attempting to pass themselves off as a typical suburban family.