短语讲解：

1. Iraqi security forces and several thousand Shi'ite militia members came together Tuesday outside the Iraqi city of Ramadi.

come together 聚会，相见;会面;汇集
例句：The parallels seem to come together in the distance.
平行线在远处看上去似交合在一起。

2. Observers say the move could add to sectarian tensions in one of the most violent parts of Iraq.

add to 增加，加强
例句：I have nothing to add to my earlier statement.
我对我先前说的话, 没有什麽补充的。