The UNIX operating system is made up of three parts; the kernel, the shell and the programs. The kernel of UNIX is the (71) of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to (72) .
The shell acts as an (73) between the user and the kernel. When a user logs in, the (74) program checks the username and password, and then starts another program called the shell. The shell is a command line (75) (CLI). It interprets the commands the user types in and arranges for them to be carded out. The commands are themselves programs: when they terminate, the shell gives the user another prompt (% on our systems).

A．interface

B．interconnect

C．changer

D．boundary

善于治疗下部痹证之腰腿疼痛，属于寒湿所致者，最宜选用的药物是( )

A．防己

B．独活

C．秦艽

D．豨莶草

E．络石藤