how long will it last 这句话对么?还是应该说how long will it last for?讲

对.用last for也可以,但一般last for后跟具体时间.如果无具体时间,一般只用last
如,
How long will the fine weather last?
好天气能延续多久?
She felt sure that their friendship would last.
她确信他们的友谊会日久天长.
She asked the nurse how long her agony must last.
她问护士,她的极端痛苦要延续多久.
当后跟具体时间时可以用last for,如,
The performance lasted for three hours.
表演持续了三个小时.
The guarantee last for two years
担保延续两年
And last for a life time.
并持续一生的时间.
Each presentation will last for 20 minutes.
每份报告应在20分钟左右.
再问： 如果还原成陈述句不是 it will last for how long么？如果这样的话前者不是错了么？换成陈述句的话就是it will last how long..it will last two days,,这样用可以么
再答： 可以。last a few days 和last for a few days 意思是一样的