if you want to catch that train,you’d better set off for the

if you want to catch that train,you'd better set off for the station _.A for a while
B all at once C once in a while D right away 顺便解释一下各项意思,

应该选D.
意思是：如果你想赶上那趟火车,你最好现在就起身去火车站.
A是”一会“的意思.
B ”突然“.
C”偶尔,有时“.
D”马上,立刻“.
从意思上就可以应该选D.