短语讲解：

1. In December, Mr. Obama and Cuban dictator Raul Castro announced the two countries had agreed to reestablish diplomatic relations.

agree to 同意
例句：They agree to the plan in principle.
他们原则上同意这个计划。

2. Secret meetings had been taking place between representatives of the two countries since 2013.

take place 发生
例句：His graduation will never take place if he doesn't get to work.
如果他不下功夫，就永远不会毕业。

3. Switzerland said it will “contribute to security, stability and prosperity in the region.”

contribute to 贡献出; 捐赠
例句：He offered to contribute to the Red Cross.
他主动提出向红十字会捐款。