2.But others have done more than dream: Since 1984, scientists at the SETI Institute in California have been searching the skies for signals from other worlds.

• 然而另一些人所做的已不仅仅是梦想：自1984年起，加利福尼亚SETI机构的科学家就一直在天空中搜寻从其它世界传来的信号。