高炉炼铁所使用的燃料主要是（），其次是喷吹燃料。
参考答案：焦炭
引起肺动脉栓塞的血栓栓子主要来自（）
A.二尖瓣
B.主动脉瓣
C.三尖瓣
D.下肢深静脉
E.肠系膜下静脉
Tom put his heart into the wildlife research, and finally, his efforts ________ him great success and fame.[ ]
A. saved
B. earned
C. made
D. offered
