您要查找的是不是：
- How long is its latent period? 它的潜伏期有多长?
- How long is the post tenable for? 这个职位任期多长？
- How long is it since we visited your mother? 自从我们看望你母亲以来到现在有多长时间了？
- How long is the warranty period? 保固期有多久呢?
- How long a variable exists is its lifetime. 变量的的确切存活时间为多长?
- How long is your period usually? 通常你的月经周期多长?
- How long is the incubation period for SARS? 非典型肺炎的潜伏期多长？
- How long is it since the electric computer came into use? 电子计算机开始应用到现在已有多久了？
- How long is menstrual hind crises, other be safety period? 月经后多久是危险期，其他都是安全期吗？
- How long is the termination period of your present position? 您现在的劳动合同什么时候结束?
- How long is the journey to the coast? 到海滨去旅行的路有多远?
- How long is the flight from Seattle to New York? 从西雅图到纽约要飞多久?
- How long is the ticket available? 这些车票的有效期有多长？
- How long is this flight going to be delayed? 这班飞机还会延迟多久？
- By the way,how long is the ticket valid? 顺便问一下，车票的有效期是几天?
- How long is it since they met each other? 她们有多久没见面了?
- How long is it since they saw each other? 她们有多久没见面了?
- How long is it since we last went to the theatre? 我们多久没去看戏了?
- How long is a senator in office? 参议员任期多长?
- How long is a student visa valid for? 学生签证的有效期限?
