i have been there (for) three times.这句话中括号中的for一定要加吗?

i have been there (for) three times.这句话中括号中的for一定要加吗? I have been there( )three times.括号里加for吗 i have been there （for） four times.这句话中括号里的for要加吗?可不可以不加? i have been there for twice 这句话有错吗 I have been asking the same question for three times from yo 这句话中为什么加个times?在句中起着什么作用I have three times as many as you. I have been to Beijing three times.这句话对three times提问该用How of 对划线部分提问 I have been there three times（three times划线） Have you ever been toShanghai,Mary?Yes,I ___ there for three I have been there for three days with my parents last month. I( ) there for three years.A went B have C haven't been Dwas Have you ever been to Shanghai?Yes,I （）there for three days