语音训练开始最适宜的时间
A.1岁
B.2岁半
C.3岁
D.5岁
E.7岁
参考答案:B
It's a nice postcard, I want to send ______________.[ ]
A. it my mother
B. my mother it
C. it to my mother
油井窜槽后,高压油层补充低压层的能量,有利于低压层采油。