今日要点:
- 抢先(抢占式)与轮询的概念
- be动词及11种表语(下) 后六种
Preemptive（抢先，抢占式）
A scheduler is said to be preemptive if it allows the running task to be suspended when a higher-priority task becomes ready. Non-preemptive schedulers are easier to implement but less appropriate for embedded systems.
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Preemptive[prɪ'emptɪv]: 抢先，先发制人
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be said to be: 被称为...
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to allow sb to do sth: 允许某人(the running task) 做(to)某事(be suspended)
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be easy to do sth: 容易做某事
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be appropritate[əˈprəʊpriət] for sth: 适合...
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embedded systems： 嵌入式
当一个高优先级的任务准备好时，充许正在运行的任务被挂起的调度策略被称为优先(抢占)。无优先(非抢占式)的调度策略更容易实现一些但适合在嵌入式系统中使用。
Polling(轮询)
A method of interfacing with hardware that involves repeatedly reading a status register until the device has reached the awaited state. Device drivers are either polling or interrupt-driven, with the latter being more generally preferred.
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interface这里做动词，用作动名词，修饰a method，to interface with，与...交互的接口
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that involves: 涉及...，做定语修饰a method
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to involve doing sth ???，应该是invove in doing sth，莫非可以省略in
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eihter ... or ... ：不是...就是...，二选一
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with sth prefered: sth做为首选
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with the latter being more generally preferred: 蛮不错的表达方式，后者越来越成为首选，可以keep it in mind（记住并牢记这句句子）
一种硬件交互方法，不断读状态寄存器，直到设备进入等待状态。设备驱动程序不是轮询的就是中断驱动的，后一种越来越成为首选的。
今日语法小知识:be动词及11种表语(下)
后六种:
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形容词:
she is beautiful
她很漂亮 -
现在分词:
The story is intersting.
故事很有趣 -
过去分词:
I am interested in the story
我对故事很感兴趣 -
介词短语:
The book is of no use.
这本书没啥用 -
地点副词:
Is he home now?
他到家了吗(home是地点副词,常用的还有here,there等) -
地点副词短语:
They are at home.
他们在家
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