● as long as ～ は、条件を示すときに使います。
¶As long as you take good care of the car, it will run.
¶As long as your work is done, it makes no difference to me what time you leave today.
¶As long as the music lasted, she was frozen, she dared not breathe.
¶As long as this bad weather lasts, we can't go hiking.
¶It's unusual for the position of chairperson to be vacant for as long as a month.
● as far as ～ は主に範囲を表すときに使います。
¶As far as I can remember, I have not seen her.
¶As far as they were concerned, everything was going well.