[填空题]红帽公司的主要产品是Red Hat ______操作系统．

[填空题]

红帽公司的主要产品是Red Hat（）操作系统。

[单项选择]Red Hat Linux内核使用RPM格式打包，因而它们易于升级和校验。如果用户需要安装内核软件包，可以使用 (19) 命令来完成该操作任务。
A. LiLo
B. install
C. rpm -ivh
D. rpm -Uvh

[单项选择]
The Red Cross would like to thank its regular donors for all their contributions. Without your help, we could not continue with our good work. Every pint of blood that you donate allows us to help people in need. Your blood saves lives. Our next blood drive will (141) on December 22nd, from 9 a.m. to 7 p.m. It will be held at the Red Cross Hall on Lion Street. We are staying open later than (142) so that working people can drop by after work. If you have donated before, please bring your registration card to save time. First time donors are also more than welcome. Please (143) your friends and family members to come along, too.
Giving up less than one hour of their time could give many more years of life to another person.
A. hold
B. be held
C. have held
D. have been holding

[单项选择]
The color red often means danger and by paying attention, (51) can be prevented. At railroad crossings, flashing red fights warn cars to stay back. A red light at a traffic intersection tells cars to stop, so (52) don’t run into other cars.
In the future, the color red also may help prevent danger (53) construction sites. Thanks to new work by engineers, bridge supports or other kinds of materials could one day contain a color-changing material. It will turn red (54) a structure collapses or falls (55) . A tiny molecule may make a big difference in future warning systems.
A polymer (56) a color-changing molecule called a mechanophore turns red seconds before it snaps. The technology may one day allow damage to materials or structures to be easily (57) .
The secret behind the color-changing material is a particular type of molecule. A molecule i
A. contacting
B. conducting
C. containing
D. considering