（）上装有活动量爪，并装有游标和紧固螺钉。 A.尺框 B.尺身 C.尺头 D.微动装

—Mum，may I watch TV this evening?

—______ You have watched it for a whole day.

A．No way!

B．Of course.

C．All right.

D．I don't know.

---I went to the beach and got plenty of rest.

--- _____ You looked tired last time I saw you.

A．I had hoped so.

B．Really?

C．I m glad you did.

D．That sounds a good idea.

秦朝郡县制与西周分封制相比较，最主要的差别在于： [ ]

A、郡县长官一概由天子任免调动，不得世袭

B、地方对天子定期朝贡并提供军赋和力役

C、是否与封国制并存

D、郡县长官在所辖领域内享有世袭统治权

二次函数y=ax²+bx+c中，若ac＜0，则函数的零点个数是______个．

机械切割设备有哪几种？