输尿管结石易停留的部位是（） A.肾盂与输尿管交界处 B.膀胱三角区 C.肾盏 D.

现有一种“十二肽”，分子式为C_xH_yN_zQ_wS(z>12，w>13)。已知将它彻底水解后只得到下列氨基酸。回答下列问题。

(1)-个该“十二肽”分子水解时需要的水分子数是_______________。

(2)将一个该“十二肽”分子彻底水解后有_______个赖氨酸和_______个天门冬氨酸。

(3)假设20种氨基酸的平均相对分子质量为125，现由四条肽链共80个氨基酸构成蛋白质，其相对分子质量为____________。

The presentation layer is concerned with the (1) and semantics of the information exchanged between two systems. The processes in two systems are usually exchanging information in the form of character(2), numbers, and so on. The information should be changed to bit (3) before being transmitted. Because different computers use different encoding systems, the presentation layer is responsible for(4) between these different encoding methods. The presentation layer at the sender changes the information from its sender-dependent format into a common format. The presentation layer at the receiving machine changes the common format into its(5)-dependent format.

空白（4）处应选择（）

A.capability

B.interoperability

C.reliability

D.dependability

斑铜矿的表面常有蓝、紫色等锖色，这属于（）。

A.自色

B.他色

C.假色

报废的烟草专用机械常用的销毁处理方式是（）、切割并熔炉。

A、砸坏

B、拆卸

C、切割

D、分离

废矿物油不属于固体废物。