1.
I haven't seen you for a long time! 好久不见！
2.
I can't imagine meeting you here! 真没想到会在这儿遇到你！
3.
Hi, long time no see! 嗨，好久不见！
4.
It's been quite a while, hasn't it? 好一阵子没见了，不是吗？
5.
I am glad to see you again. 很高兴再次见到你！
6.
What a surprise to meet you here! 想不到在这里见到你！
7.
Where have you been hiding lately? 这段时间你躲到哪里去啦？
8.
What a pleasant surprise running into you!真想不到会碰到你！
9.
Fancy meeting you here!真没想到在这儿见到你！
10.
Never thought I'd see you here!万万没想到在这里遇到你！