养路机械根据重量可分为轻型和重型两类。
参考答案：对
影响燃烧特性的参数主要有（）。
A、燃气热值
B、相对密度
C、燃烧速度
D、燃料
It is important for families to observe their traditions even as their children get older.
A. notice B. watch C. celebrate D. follow
