钢水中2[Al]+3[Fe]＝（Al2O3）+3[Fe]的反应是（）反应。
A．吸热
B．放热
C．不吸热也不放热
参考答案：B
I'm sorry, I can't play soccer with you this afternoon. I ____ too much homework to do . [ ]
A.do
B.had
C.have
D.did
知识产权的专有性
