I don’t know how long it’ll be 　　　 I get the bandage off my

选A。考查状语从句。此处句意为: 我不知道还要多久我才能取下胳膊上的绷带。此处before意为“(表示要先发生某事或过一段时间之后才会发生另一件事)在……之前”。
【变式训练】
(2013·杭州模拟)—So you know Catherine?
—Yes, it was last week 　　　 she came to visit my roommate Jane.
A. that B. when C. since D. before
选B。考查强调句的省略用法。答句句意: 是的, 是在她上星期来拜访我室友Jane的时候我认识她的。last week后when所引出的是定语从句, 完整的回答是: It was last week when she came to visit my roommate Jane that I got to know Catherine. 所以答案选B。