X线管阴极的作用是（） A.发射并聚焦电子 B.只发射电子 C.只聚焦电子 D.散热

根据语篇内容，用恰当的短语填空，使之意思完整。

     Thanks for your invitation. I'm sorry I can't visit you this week. I am __1__. This evening I'm going

to my cousin's house. It's my cousin's birthday. Today I have a toothache, so I have to see the dentist

tomorrow. On Friday, there will be a math test, and I __2__. On Friday evening, a new film will be on,

and I'm __3__ with my friends.

企业风险管理过程中，面临的最广泛的无形成本是( )。

A．授权费
B．破坏和机会成本
C．维修费
D．信息技术的实施和整合成本

对于函数y=2x-1，当自变量增加m时，相应的函数值增加[ ]

A．2m

B．2m-1

C．m

D．2m+1

疥灵丹功效与作用

现场检验时，还应检查哪些不合理的计量方式？