Jack Kennedy was a friend of mine.

杰克·肯尼迪是我的朋友。

In contrast, Jack Kennedy believed that the government should help make peoples' lives better.

相比之下，杰克肯尼迪认为政府应该帮助改善人们的生活。

The greatest crisis of Jack Kennedy's presidency began on the morning of October 16, 1962. Again, it involved the island of Cuba.

杰克肯尼迪总统任期内最大的危机始于 1962 年 10 月 16 日上午。它再次涉及古巴岛。

The " opposition" refers to the people you are trying to beat, or in this case Richard Nixon, who was the Republican candidate whom, in fact, Jack Kennedy did beat in the 1960 election.

“反对派” 指的是你试图击败的人， 或者在本例中是理查德尼克松， 他是共和党候选人，事实上，杰克肯尼迪在 1960 年的选举中确实击败了他。