Mr Li has some trouble sleeping, so dinking a glass of milk before going to bed every night is his common_____．

A．practice

B．knowledge

C．experience

D．duty

一种精密零件按5：1画在图上长是1厘米，实际长度是（    ）cm，如果实际宽是0.1cm，那么图上宽是（    ）cm。