A：发出黄白色火焰
B：固态石蜡变成了液态
C：生成了二氧化碳和水
D：放出了大量的热
2014年
2015年
2016年
养宠物狗比率
12%
8.2%
7.5%
养宠物猫比率
3.1%
4.3%
5.4%
After you learn about the lives of the pilots, especially their hard training, you can decide ______ you want to become a pilot or not.
