误He will have a seven days' holiday next month.
正He will have a holiday of seven days next month.
正He will have a seven-day holiday next month.
正He will have seven days' holiday next month.
析在表示“放多少天假”时只能用a holiday of...days或...days holiday。
她要去香港度假。误She's going on holidays to Hong Kong.
正She's going on holiday to Hong Kong.
析holiday用于短语go〔be〕 on holiday时,只用于单数形式。