技能学习最基本的条件是()
A.讲解
B.示范
C.练习
D.反馈
参考答案：C
解析：技能是通过练习获得的，这是技能学习最基本的条件。
The boy was in _________danger of losing his life, but __________most famous doctor saved his life.
A. the ; a B./; the C. the; the D/;a
The color of the signal flare sent up by a submarine about to surface due to an emergency condition within the submarine is（）.
A.green
B.red
C.white
D.yellow
