Because, Because of, As; which, where, when______a dreadful illn

Because, Because of, As; which, where, when
______a dreadful illness, days are gone ______local 5-star hotels charged $1,000 for one night.
【正确答案】：Because of/when
【题目解析】：关系副词when引导关系从句修饰表示时间的先行词，在关系从句中充当时间状语。