VOA慢速英语:US Investigates, National Guard Arrives in Ferguson

短语讲解：

1. But what is important is that the security forces have arrived at the dam and they were able to capture the dam and conduct a full check around it to make sure that it's empty of bombs and explosive charges.

arrive at 到达; 来到
例句：I arrive at my hotel late in the evening.
傍晚时分，我到达了预定的酒店。
make sure 把事情弄清楚，核实或查明某事物
例句：I'll have to make sure I'm not chased. 
我一定想办法不叫他们发现。 

2. However, a rebel spokesman denied his forces were involved in the attack.

involve in 使参与[陷入，牵扯到]
例句：Be you involve in the copyright affair.
你是否卷入著作权的事件之中。

3. Pope Francis called for better relations between North and South Korea.

call for 去接（某人）; 去取（某物）; 需要; 要求
例句：Different circumstances call for different tactics. 
不同的情势需要不同的策略。