若∠a=13°37′48″,则∠a的补角的大小是______度.
∠α的补角=180°-13°37′48″=166°22′12″=166.37°.故答案为166.37°.
猎豹是动物世界的短跑冠军,速度可达28m/s,则经过0.5min,它能跑多远?
They met, ______ a few greetings and then settled down to their own business. [ ]
A. changed
B. spoke
C. exchanged
D. traded