She used to do a lot of____ when she was in Norway .A.skating B.skate C.skated D.to skate为什么选A,请详解并翻译这句话,

She used to do a lot of____ when she was in Norway .A.skating B.skate C.skated D.to skate
为什么选A,请详解并翻译这句话,

她在挪威的时候经常去滑冰.
do skating,就是滑冰.do后面接动词+ing.