我在 Oracle Linux 5.1 上运行。应用程序提交打印的作业正在进入打印队列，但没有被清除。如何解决这种情况？
$ lpstat -t
printer MATERIALSJD3 now printing MATERIALSJD3-7. enabled since Mon 13 Nov 2017 03:26:37 PM MYT
MATERIALSJD3-1 appltest 10240 Mon 13 Nov 2017 03:26:37 PM MYT
MATERIALSJD3-2 appltest 10240 Mon 13 Nov 2017 03:29:35 PM MYT
MATERIALSJD3-3 appltest 10240 Tue 14 Nov 2017 08:52:15 AM MYT
MATERIALSJD3-4 appltest 10240 Wed 15 Nov 2017 12:50:46 PM MYT
MATERIALSJD3-5 appltest 7168 Thu 16 Nov 2017 03:09:38 PM MYT
MATERIALSJD3-6 appltest 10240 Fri 17 Nov 2017 09:09:11 AM MYT
MATERIALSJD3-7 appltest 7168 Fri 17 Nov 2017 03:47:19 PM MYT