R-f preselectors
[電] 射頻預選器
??? 情景例句
When did the Roman Empire come into being?
羅馬帝國是什么時候形成的？
His heart cannot be pure whose tongue is not clear.
嘴不凈者心不純。
What happened on the march then?
那么 ，在游行中發生了什么事？