张：小王昨天就感冒了，没想到今天还来上课。－》李：他虽然感冒了，可是还是来上课。 (but he still came to classes) 张：这件衣服价钱不算便宜，你真的要买吗？ －》李：这件衣服虽然比较贵，可是很漂亮。 (還是 means to emphasis the former sentence. lt's like "still" in English. 可是 means but, however...) 张：你怎么不认识他？你们不都是去年从纽约大学毕业的吗？－》李：我们都虽然从同一所大学毕业的，可是我们从来没碰(到)過。 (you have already said 從來, so you have to add 過 to express the status that you have never done) 张：你们有钱，给他一点，有什么关系嘛！－》我们虽然有钱，可是我們連一點錢都不想给他。 / 你們有錢，卻連一點也不肯給他。 有什麼關係 means "it doesn't matter. " or "it doesn't bother you at all." Cus the sentence here means "you guys have money, why dont you give him some? it does'nt matter. " On the contrary, "it bothers me." means 有關係。

“虽然……可是……”is hardly used in Chinese.When we want to express the similar meaning as "but" or "although",We Chinese ofen use "虽然……但是……"instead of "虽然……可是……".For example,"这件衣服虽然比较贵，但是很漂亮。"From the standpoint of Chinese,it is a kind of common collocation.Are these sentences all written by yourself?Your Chinese is good*^_^* The above sentence “有什么关系嘛” in that scene means "how about…" or "why not…" How about share some money with them now that you have so much money. (I hope this answer can benefit you.)

张：小王昨天就感冒了，没想到今天还来上课。－》李：他虽然感冒了，可是还是（add "是"sounds more idiomatic）来上课了。 张：这件衣服价钱不算便宜，你真的要买吗？ －》李：这件衣服虽然比较贵，但是很漂亮。 张：你怎么不认识他？你们不都是去年从纽约大学毕业的吗？－》李：我们虽然都是从同一个大学毕业的，可是我们从来没碰到过。 张：你们有钱，给他一点，有什么关系嘛！－》你们虽然有钱，可是却不想给他。 "有什么关系嘛"means you gave money to him, you are not gonna get in trouble or lose a lot. I'm not a professional Chinese teacher, we seldom learn chinese grammar, so I just correct the thing that I think is not right,I hope it's helpful.:)