I’m happy [that you’ve decided to come].
 Many English speakers today are surprised [that Early English would be
unintelligible to them].
I would strongly recommend dropping the terms 'noun clause', 'adverb clause' etc. The classification of finite subordinate clauses is based on their internal form rather than spurious analogies with the parts of ...
According to dictionary.com, since 1350 A.D. to 1400 A.D.:
First recorded in 1350–1400; Middle English, from Middle French, from
Latin situs “position, arrangement, site” (presumably originally,
“leaving, setting down”), equivalent to si-, variant stem of sinere
“to leave, allow to be” + -tus suffix of verbal action
You can find this information in many ...