Dear Mr.Brown,

I am sorry to t__小题1:_ you my mother is ill.She c_小题2:day and night .She does not l_小题3:_down and have a rest .My father is not in .He w_小题4:_to Beijing last week. My mother can not look after h _小题5:. The doctor gives her some ___小题6:( 建议).she should stay in bed and _小题7:_(服用) some medicine .So I have to take c_小题8:_of her._ 小题9:_ (可以)I  ask for a day’s  leave?

Thank  you.

Yours  s__小题10:___,

Tom

钻削时的切削热大部分由（）传散出去。

A.刀具 

B.工件 

C.切屑 

D.空气