由于加热炉的辐射段炉管附有钉头，燃烧燃料油时会附着所生成的炉灰，所以要设置吹灰器定时吹灰，以保证炉管传热效果。（）
参考答案：错
— What doesn't have fur? — ___________[ ]
A. A horse.
B. A chicken.
C. A fish.
Children should be instructed to put things ________ they belong in their early childhood.[ ]
A. where
B. in which
C. to which
D. what
