A:珍妮纺纱机的发明
B:瓦特改良蒸汽机
C:火车、轮船的出现
D:内燃机的发明
“女大十八变,越变越好看”你认为发生这种巨大变化的时期主要集中在( )
—We are supposed to visit him from time to time. Then he won't feel _______.