【简答题】A good vocabulary is like an _________ _______.
【单选题】Vocabulary learning is an process between input and output.
【单选题】The English vocabulary is a(an) ______ system of codes.
【单选题】Vocabulary is an ___________ part in English learning.
【简答题】___________ is a term to refer to the phenomenon that vocabulary is an integrated system interrelated in sense and can be divided into semantically related sets or fields.