状语从句：时间、地点、原因、结果、条件、目的、让步、程度、比较与方式状语从句及其从属连词与连接短语

. Jasmine was holidaying with her family in a wildlife park ________ she was bitten on the leg by a lion.

  A) when          B) while         C) since           D) because

状语从句：时间、地点、原因、结果、条件、目的、让步、程度、比较与方式状语从句及其从属连词与连接短语
. Jasmine was holidaying with her family in a wildlife park ________ she was bitten on the leg by a lion.

once引导的条件状语从句，省略了it is。