[单项选择] A non-root user can run rsh commands from serverA to serverB， but attempts to run rsh  commands by the root user return with a permission error message. What action will resolve the problem？（）
A. Add root user to the /etc/hosts.equiv on serverB .
B. Create $HOME/.rhosts file for the root user on serverB .
C. Restart the rshd daemon with root enabled option on serverB .
D. Add entry to allow root user from serverA to the /etc/hosts.allow on serverB .

[判断题]HFD类型冷剂包括R23、R32、R41、R125、R134、R143、R152。

[判断题]电阻R1，R2并联，已知R1＞＞R2，并联后的等值电阻近似等于R1，即R≈R1。

[判断题]氯氟烃类产品，简称CFC，主要包括R11、R12、R113、R114、R115、R500、R502等，由于对臭氧层的破坏作用不大，被《蒙特利尔议定书》列为受限物质。

[多项选择] Routers R1, R2, R3, and R4 connect to the same 10.10.10.0/24 LAN- based subnet. OSPF is fully working in the subnet. Later, R5, whose OSPF priority is higher than the other four routers, joins the subnet. Which of the following are true about the OSPF database exchange process over this subnet at this point?（）
A. R5 will send its DD, LSR, and LSU packets to the 224.0.0.5 all - DR - routers multicast address.
B. R5 will send its DD, LSR, and LSU pack ets to the 224.0.0.6 all - DR - routers multicast address.
C. The DR will inform R5 about LSAs by sending its DD, LSR, and LSU packets to the 224.0.0.6 all- SPF - routers multicast address.
D. The DR will inform R5 about LSAs by sending its DD, LSR, and LSU pa ckets to the 224.0.0.5 all- SPF - routers multicast address.

[判断题]表达式"R1=R2+R3*SIN（R4）"的运算次序依次为SIN（R4），R3*SIN（R4），R2+R3*SIN（R4）（SIEMENS系统）。

[判断题]设R是非空集合，R和R的笛卡尔积到R的一个映射就是运算。

[名词解释]r线组

[单项选择]如下两个关系R1和R2，它们进行何种运算后得到R3R1

[判断题]无氟空调器的制冷剂R407C由R23、R25、R125三部分组成。

[多项选择] Routers R1 and R2 are EIGRP neighbors. R1 has been configured with the eigrp stub connected command. Which of the following is true as a result？（）
A. R1 can learn EIGRP routes from R2, but R2 cannot learn EIGRP routes from R1
B. R1 can send IP packets to R2, but R2 cannot send IP packets to R1
C. R2 no longer learns EIGRP routes from R1 for routes not connected to R1
D. R1 no longer replies to R2's Query messages
E. R2n o longer sends to R1 Query messages

[判断题]海尔无氟空调器制冷剂为R407C，成分由R32、R125、R134a组成，比例分别为R32为23％；R125为25％；R134a为52％。

[单项选择]已知R1=8，R0=9，执行指令MOV R0，R1，LSR#3后，R0的值为（）。
A. 1
B. 8
C. 0x10
D. 0x80

[填空题]电阻R₁和R₂串联，已知R₂＝4R₁，若R₂两端电压U₂=16V，则R₁两端电压U₁＝（）。

[单项选择]Suppose V₁=＜R,+＞,V₂=＜R, ·＞,where R is the set of real numbers, +and · are respectively addition and multiplication. Let f: R→R and {(x) = 10x, which of the following propositions is true ( )
A. f is an injective homomorphism from V₁ to V₂
B. f is a surjective homomorphism from V₁ to V₂
C. f is an isomorphism from V₁ to V₂
D. none of the above

[单项选择]指令“LDMIAR0!，{R1，R2，R3，R4}”的寻址方式为（）
A. 立即寻址
B. 寄存器间接寻址
C. 多寄存器寻址
D. 堆栈寻址

[填空题]已知R₂和R₃并联后，再与R₁组成串联的电路，外加总电压为27V，且R₁＝7Ω，R₂＝6Ω，R₃＝3Ω，则流经R₂的电流为（）。

[单项选择]已知R3=0x80001000，R4=0x00A00010，执行ARM指令MOV R3，R4，LSL#8后，R3的值为（）。
A. 0x80001000
B. 0x00A00010
C. 0xA0001000
D. 0x0000A000

[多项选择] In a lab, R1 connects to R2, which connects to R3. R1 and R2 each have several working interfaces, all assigned addresses in class A network 10.0.0.0. Router R3 has some working interfaces in class A net work 10.0.0.0, and others in class B network 172.16.0.0. The engineer experiments with the auto -summary command on R2 and R3, enabling and disabling the command in various combinations. Which of the following combinations will result in R1 seeing a rout e for 172.16.0.0/16, instead of the individual subnets of class B network 172.16.0.0?（）
A. auto - summary on R2 and no auto - summary on R3
B. auto - summary on R2 and auto - summary on R3
C. no auto -summary on R2 and no auto- summary on R3
D. no auto - summary on  R2 and auto - summary on R3

[简答题]已知8个无符号数之和存于R3 R4，求其平均值，结果仍存于R3 R4中，请编程实现（R3为高字节）。