The boy was so tired that he fell asleep ________ his mother could take off his clothes.[ ]

A. before  

B. after

C. while  

D. when

检查铆钉头与蒙皮贴合度，允许在铆接缝中有10％的铆钉，其壳体头周长三分之一上铆钉壳体的不紧密贴合不大于（）㎜。

A.0.1

B.0.2

C.0.3

D.0.4