After the final exams I will have a vacation in Hainan.A. 5 dayB. 5-dayC. 5 daysD. 5-day

问题补充：

After the final exams, I will have a vacation in Hainan.

A. 5 day

B. 5-day

C. 5 days

D. 5-days

答案：

A. 5 day

(答案→)B. 5-day

C. 5 days

D. 5-days

解析：此题重点考查合成形容词的基本构成，数词+名词(+形容词)；合成形容词中的名词(year, hour, metre, month等)必须用单数形式。