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

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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。