1. It was the enemys boast of impregnability that caused their own defeat.

2. RIM's guarantee of the impregnability of customers' encryption keys is also less impressive than it appears.

3. The Yulong Jokul is famous for its impregnability. She got the name Yulong because her figure is like a jade dragon armed with 13 swords pointing to the sky.

4. The castle's great glory - its massive, twin-towered gatehouse - maintains an air of impregnability.

5. The second, control of solid content of size can finely control size loading of strand, and then impregnability of strand is improved.