We were all very much attracted by the beautiful scenery________we set foot in the village. [ ]

A. quickly  

B. suddenly

C. finally  

D. immediately

一个在地球上做简谐运动的单摆，其振动图象如图1所示，今将此单摆移至某一行星上，其简谐运动图象如图2所示．若已知该行星的质量为地球质量的2倍，求该行星的半径与地球半径之比．