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1·Unless these questions are solved, the region will remain a powder keg.

除非这些问题得以解决，否则该地区会一直是个火药桶。《柯林斯英汉双解大词典》

2·What was once a forest becomes a virtual powder keg of untapped fuel.

森林就变成了未开启的虚拟引火气罐。

3·The fact that the two vessels did sink is an unalterable fact of history, and while ship design and safety protocols have changed, the powder-keg nature of human behavior is the same as it ever was.

两艘船确实沉没了的事实是不可改变的历史事实，虽然船的设计和安全条款已经改变，但是，人类行为的火药库本质一如既往，没有改变。

4·On the night of 7 September 1776, the Turtle tried to attach a keg of powder to the British ship Eagle. The attempt failed and the powder exploded harmlessly.

1776年九月七日晚，海龟号想把一桶炸药附在英国的苍鹰号上，但不成功，炸药空自爆炸。