The main purpose of warming the parts of the main engine is ()
A. to reduce heat stress
B. to reduce low temperature corrosion
C. to improve firing and starting performance
D. fuel saving
我认识小王子多久后了解到小王子生活环境的凄凉?()
A. 第七天
B. 第四天
C. 第三天
D. 第二天
湿地松的叶为()。
A. 2针1束
B. 3针1束
C. 2和3针1束并存
D. 5针1束