As is known to all language learners newly learnt words will soon be forgotten unless us

问题补充：

As is known to all language learners, newly learnt words will soon be forgotten unless used in everyday communication.

A. exactly

B. finally

C. gradually

D. frequently

答案：

A. exactly

B. finally

C. gradually

(答案→)D. frequently

解析：考查副词。A.exactly精确地，准确地，确切地B.finally最后，终于C. Gradually逐渐地D.frequently频繁地，屡次地。句意：所有语言学习者都知道，新学的单词很快就会忘记除非在日常交流中频繁地使用。