User programs interact with the kernel through a set of standard(71). They request services to be provided by the kernel. Such services would include accessing a file: open close, read, write, link, or execute a file; starting or(72)accounting records; changing ownership of a file or(73); changing to a new directory; creating,(74), or killing a process; enabling access to hardware devices; and setting limits on system resources. Unix is a multi -user, multi -tasking operating system. You can have many users logged into a system simultaneously, each running many programs. It's the kernel's job to keep each process and user separate and to regulate access to(75), including cpu, memory, disk and other L/O devices.
A．system commands
B．system transfer
C．system calls
D．system rings
模块内聚度是用来衡量模块内部各个成分之间彼此结合的紧密程度的，模块的内聚度可以分为以下几个层次。
①一组语句在程序的多处出现，为了节省内存空间把这些语句放在一个模块中，该模块的内聚度是(1)的。
②将几个逻辑上相似的成分放在一个模块中，该模块的内聚度是(2)的。
③模块中的所有成分引用共同的数据，该模块的内聚度是(3)的。
④模块内的某成分的输出是另一些成分的输入，该模块内聚度是(4)的。
⑤模块中所有成分结合起来完成一项任务，该模块的内聚度是(5)的。它具有简明的外部界面，由它构成的软件易于理解、测试和维护。
A．功能性
B．顺序性
C．通信性
D．过程性
E．偶然性
设A和B是两个单链表，其表中元素有序递增。请分析算法的时间复杂度。其时间复杂度为(40)。
A．O(re+n-1)
B．(m+n+1)
C．O(m+n)
D．不确定
Sequential circuit is a common logic device whose output values, at a given instant, depend upon its input values and the internal state at that instant, and whose internal state depends upon the(66)preceding input values and the preceding internal state. A sequential circuit can assume a finite number of internal states and may therefore be regarded, from an abstract(67), as a finite(68).Combinational circuit is another logic device whose output values, at any given instant, depend upon the input values at that instant. A combinational circuit is a(69)of a sequential circuit whose internal state is not taken(70).
A．directly
B．immediately
C．instantly
D．snapshot