你勉为其难干啥？为啥不用我写的问题？要说历史，我前面写过，还有一个你忘了1916年

In 1916， Denmark and the US signed the Treaty of the Danish West Indies, and the colony became the US Virgin Islands. The US feared that Germany might seize control of the islands during WWI. The US recognized Denmark's full sovereignity over Greenland. 

do you understand this?