写出下列词语的近义词或反义词。
近义词:骤然( ) 忧郁( ) 犹豫( )
反义词:镇定( ) 忧郁( ) 犹豫( )
(1)突然 郁闷 迟疑
(2)慌张 高兴 坚定
We were told that we should follow the main road _____ we reached the central railway station . [ ]
A. whenever
B. until
C. while
D. wherever
排除冷凝水的方法主要有()和()两种。