Mostly it’s obvious: Silva is the country’s the most common surname and José one of its most common first names, so referring to Marina and Serra makes more sense.
原因多半很明显：Silva在巴西是最常见的姓氏，而José也是最常见的名字之一，所以分别称呼他们Marina和Serra可说别具用心。
Also, I believe common sense is not so common anymore!
另外，我感觉常识也不再是常识。
Common sense is not so common.
(普通的)常识，其实不那么普通。
Common sense is not so common.
(普通的)常识，其实不那么普通。
应用推荐