have hard times对不对? have a hard time 在这time是不可数的 为什么可以加a?

have hard times对不对? have a hard time 在这time是不可数的 为什么可以加a? have a very hard time have a hard time造句 have a hard time doing 还是have hard time doing have a hard time with的with在这儿是什么意思? have a good time 其中time不可数为什么加a? have a hard time have a difficult time 区别 have a hard time doing sth "have a hard time doing"和"have hard time to do"有区别吗? have a hard time with 和 have problems with可以互换么 hard time .In winter,animals have a hard time finding anythi what a funny time to have breakfast!time是不可数名词,为何what后加a