A c（） sentence contains two or more clauses， one of which is incorporated in the other.

A r（） is often seen as part of a word， but it can never stand by itself although it bears clear， definite meaning. 点击查看答案

Clear [1] and dark[]are allophones of the same one phoneme 1 .They never take the same position in sound combinations， thus they are said to be in c（） distribution. 点击查看答案