单项选择题
In English, “pill” and “bill” are （）.
A.a phonemic contrast B.complementary distribution C.assimilation D.a minimal pair
单项选择题 As modern linguistics aims to describe and analyze the language people actually use, and not to lay down rules for "correct" linguistic behavior,it is said to be （）.
名词解释 Duality
问答题 Describe the process of language perception，comprehension and production.
