That's why your operating systems and your personal computers often crash for no apparent reason. Just because two things happen to, once in a while, occur at the same time.

这就是为什么你的电脑或者操作系统,经常会毫无预兆的崩溃了,这是因为两件事情正好同时发生了，通常还有人工输入。

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So it'll be a time once or twice a week where they will be in their office.

所以，他们大概每周有一两次会在办公室里。

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Once the poleis are in place, they will spend a great deal of time fighting each other.

一旦城邦在某地建立,他们就会花上很长一段时间相互争斗

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So rather than go through this again a whole third time, I've gone through it once in quantities and once in prices, I'm going to get you guys to do it this time by having you do it on a homework assignment.

与其从头到尾再做第三遍,我已经从产量和价格角度从头到尾做过了,我将让你们自己,在家庭作业中完成这个工作

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