虽然…但是/可是….

The construction虽然…但是/可是….

“虽然…但是/可是….”, meaning “although”, is used to link two contradictory statements. “虽然”may go either before or after the subject of the first clause, while “但是”(or “可是”) is always placed at the beginning of the second clause.

For example:
虽然他从来没有看过这部小说，但是他很早就听说过。 
我虽然喜欢西方的油画，可是不会画油画。
“虽然”can also be omitted. For example:
他（虽然）学汉语的时间不长，但是学得很好。