I feel it's necessary for me to visit them.我觉得拜访他们是必要的。

今天的几个例句都是有关说明自己有义务的：1. I should get there earlier. 2. I must write him a letter.3. I'm expected to call her back.我得给她回电话。 4.I feel it is my duty. 我觉得我有义务。