下列生活情景中,通过做功来改变物体内能的是( )
A:金属汤勺放在热汤中,温度升高
B:冬季人们常用热水袋取暖
C:铁丝被反复弯折,弯折处发热
D:食品放在冰箱中,温度降低
____the doctors in their hospital is about one thousand, and sixty percent of them___________ women.
“等角的补角相等”的条件是____ ,结论是____.