Particles for Contradictory Conjunction

私はゴーヤが大嫌いだが、健康のために食べている。 I hate bitter melon, but I eat it for my health.

私の給料は安いが、会社に対する忠誠心は持っている。 Although my salary is low, I feel loyal to the company that I work for.

The particle が can be replaced by けど, けれど or けれども without changing the meaning. These four particles are interchangeable.

(A) 私はゴーヤが大嫌いだが、健康のために食べている。 I hate bitter melon, but I eat it for my health.

(B) 私はゴーヤが大嫌いですが、健康のために食べています。 I hate bitter melon, but I eat it for my health.

(C) 僕はゴーヤが大嫌いだけど、健康のために食べてるんだ。 I hate bitter melon, but I eat it for my health.

(C’) 私はゴーヤが大嫌いだけれど、健康のために食べてるんだ。 I hate bitter melon, but I eat it for my health.

(C’’) 私はゴーヤが大嫌いだけれども、健康のために食べてるんだ。 I hate bitter melon, but I eat it for my health.

Sentence (A) is not suitable for conversing but for writing. Sentence (B) is suitable both for conversing and writing as a polite one. Sentence (C), (C’) and (C’’) are suitable for conversing. Among them, (C) is the most colloquial and natural.

The particle が is mainly used for contradictory conjunction but it can be used after prefatory statements.

私はこの本を買いますが、あなたはどうしますか？ I will buy this book. How about you?

ちょっと教えてほしいのですが、郵便局はどこですか？ If it's not too much trouble, could you please tell me where the nearest post office is?

さやかの件ですが、もう少し詳しく話していただけませんか？ Could you please tell me the details of the situation involving Sayaka?

Particles for contradictory conjunction can be used as sentence-ending particles. 

あのう、（あなたの声が）聞こえないんですけど。 Excuse me, I can’t hear you well.

（あなたが）そこにいるとテレビが見えないんですが。I can't see the television set with you standing there.

Technically, as for the above sentences, it is regarded as the prefatory usage of conjunction particles. The particle けど, as well as が, indicates that the statement is a preface, so the listener has to guess the remainder of the sentence, which was omitted.

（あなたの声が）聞こえないんですけど（＝もう少し大きな声で話してくれませんか） I can’t hear you well (so please speak more loudly).

そこにいるとテレビが見えないんですが（＝どいてくれませんか）。 I can't see the television set with you standing there (so please move).

Japanese Version
http://meadowlake001.blogspot.jp/2015/06/particles-for-contradictory.html