He noticed the helicopter hovering over the field. Then to his astonishment, he saw a rope ladder _____ out and three men climbing down it.
B
暂无解析
_____yourtimelyadvice,Iwouldneverhaveknownhowtogoaboutthework.
Toobtainasatisfactoryresult，onemustapplytwo____ofpaintonacleansurface.
Itisimperativethatstudents_____theirtermpapersontime.