短语讲解：

1. Followers of the White House Snapchat will get a behind-the-scenes look at the final preparations before Obama’s speech.

look at 看; 审视; 评判
例句：Now, look at this horse. This part is called the saddle.
注意看这匹马，这部分为鞍部。

2. The White House said in a blog post that the Snapchat account adds to its social media presence.

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.

3. Fellow politicians have tweeted about taking part in the live story:

take part in 参加…，参与…活动
例句：Are you going to take part in the first experiment?
你们会参与首次实验吗?