I think they did not have fun on their day offi---- ----- they------ontheir day off是一个复合句简单句：一个句子只有【一个】主谓结构，无论长短。如 I love you.复合句：一个句子包含两个或两个以上主谓结构。如 I love you and you love me. (并列复合句） I love what you are. （主从复合句）I—————— ————————they——————————ontheir day off这种形式填空I didn't think they have fun on their day offthey后只有一个空一个空没法填吧 一个空得把单词换了I didn't think they enjoyed on their day off