静夜玄霜
I have gone to Hefei. 我已经去合肥了,意味着人不在合肥现在。I went Hefei . 我去了合肥。 强调我当时去了合肥这个动作。I have been to Hefei. 我去过合肥。强调曾经去过。选择你向表达的语境再选择比较好。
素雪清芳
Hefei is an open city of science and technology, the ***company is a modernized enterprise. Let us join hands and work together to create a bright future.