Not until Kentucky’s Mammoth Cave had been completely explored in 1972_________
Đáp án C
– cấu trúc Not until + N/mệnh đề, mệnh đề đảo: không cho đến tận khi.
Ann's encouraging words gave me _________ to undertake the demanding task once again.
He did not share his secrets with other people but he ________in her.
The local people insisted that the road_________50 cm more so that, in case of flood, they still can travel on it.
The girl __________ design had been chosen stepped to the platform to receive the award.