单项选择题 Lack of attachment is ________, which equals to inner freedom and the ability to make and accept changes, take advantage of opportunities and adopt new habits. （ ）A.seclusion B.solitude C.alert D.detachment

单项选择题 在单处理机系统实现并发后，以下说法正确的是（ ）。 A. 各进程在某一时刻并行运行，CPU与外设之间并行工作 B. 各进程在某一时间段并行运行，CPU与外设之间串行工作 C. 各进程在某一时间段并行运行，CPU与外设之间并行工作 D. 各进程在某一时刻并行运行，CPU与外设之间串行工作

单项选择题 By the mid-1920s, American film industry came into the hands of a few powerful companies, which controlled production, distribution and exhibition. Normally, they were called “the Big Five” and “the Little Three” as well.________