21.－Why didn' t you answer the phone this afternoon?－We didn

21.－Why didn' t you answer the phone this afternoon?－We didn' t hear it.I21.－Why didn' t you answer the phone this afternoon?－We didn' t hear it.I was in the garden and Mum __________ a shower.[ A ] has had [ B ] had[ C ] had been having [ D ] was having选B还是D?