短语讲解：
1. A series of explosions and attacks hit cities and towns across Iraq Monday, killing at least 63 people.
a series of一系列
例句：The post office will issue a series of new stamps.
邮局将要发行一套新邮票。
2. He said that our intelligence led us to believe, after security briefings, that there would be widespread violence, especially since we're expecting [a pilgrimage] at the Imam Ali shrine which was no doubt a pretext for the explosions.
lead to导致, 引起
例句：This led us to make a summing up of the experience and lessons.
这促使我们对经验和教训进行�
