Leave your key with a neighbor ____ you lock yourself out one da

Leave your key with a neighbor ____ you lock yourself out one day.
A、ever since
B、even if
C、soon after
D、in case
【正确答案】：D
【题目解析】：把钥匙留给邻居的目的是防止有一天把自己关在门外，因此该空应填in case引导目的状语从句。