美国有线新闻 CNN 摩苏尔收复战推进顺利 大量平民逃离家园（在线收听）

First today, we're taking you to the Middle East. The northern part of Iraq is where you'll find the city of Mosul. On one side of the ongoing battle for it, ISIS terrorists who took over Mosul when the Iraqi army fled in 2014. On the other side, Iraqi troops who were fighting to get it back, along with the help of U.S. and other international forces.

Mosul fell to ISIS in just four days. The battle to force ISIS out has been going on since October. The terrorists have dug tunnels. They've set traps. They've rigged cars with explosives. The Iraqi-led troops have heavy weapons, tens of thousands more fighters and the support of U.S. air power.

The civilians trapped in between had been fleeing from the city in record numbers since the fighting began. The United Nations says 4,000 people a day have been displaced by the battle since February 19th. It's not known how much of Mosul will be habitable when the fight for it ends. But as that end approaches, Ben Wedeman examines why this one city is so significant to both ISIS and Iraq.

BEN WEDEMAN, CNN SENIOR INTERNATIONAL CORRESPONDENT: The one thing you need to know about the fight for Mosul is that this battle could decide the fate of ISIS.

The extremists seized control of Mosul, Iraq's second largest city in June 2014. What followed was a series of lightning conquest in Iraq and Syria that brought ISIS to the attention of the world. It was in Mosul that ISIS leader Abu Bakr al-Baghdadi declared his so-called caliphate. His supporters favored slogan was that the Islamic State is here to stay and will spread.

Well, what a difference two and a half years make. The tide has turned. Iraqi forces have seized one city after another. They've already taken control of the eastern part of Mosul and are now pressing ahead in the west.

The area controlled by Baghdadi's so-called caliphate is steadily shrinking. The caliphate's appeal is dimming. ISIS no longer puts out slick propaganda videos crowing about the good life in Mosul.

The war to destroy ISIS, however, is far from over. The group still controls pockets in Iraq and large parts of Syria, and its hardcore supporters are likely to fight to the death.

But the loss of Mosul, the largest city, once under ISIS control, will be a deadly blow.