These islands were a crucible of exploration and development.是什么意思？

These islands were a crucible of exploration and development.

这些岛屿是对开发和发展的严峻考验.

these

adj. 这些的；pron. 这些；

例句
There's lots of money about these days for schemes like this.
近来这类计划资金充足。

islands

n. 岛，岛屿( island的名词复数 )，群岛；

例句
The Aleutian chain is a long arc of islands in the North Pacific.
阿留申群岛是北太平洋上一长串呈弧形排列的小岛。

were

be的过去时复数和第二人称单数形式，有时代替 was,用于条件从句、动词 wish 之后等；

例句
Shops, houses, and vehicles were set ablaze.
店铺、房子和车辆全都陷于火海。

crucible

n. 坩埚，熔炉，严峻的考验，磨

例句
...a system in which ideas are tested in the crucible of party contention...
各种观点得以在党派纷争的严峻考验中得到检验的体系

of

prep. 关于，属于…的，由…制成；aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气]；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

exploration

n. 探测，勘探，探险，搜索，研究，[医]探查术；

例句
...the risks attendant on the exploration of the unknown.
探索未知所带来的危险

and

conj. 和，与，而且，于是，然后，因此；

例句
I spend a lot on expensive jewelry and clothing...
我花很多钱购买昂贵的首饰和衣服。

development

n. 发展，进化，被发展的状态，新生事物，新产品，开发区；

例句
The 1985 federal budget allocated $7.3 billion for development programmes...
1985年的联邦预算将73亿美元拨给了开发项目。