He was talking about "a thousand marbles" to someone named "Tom".

他正在和一个叫“汤姆”的人讲着什么“1,000颗玻璃弹珠”的事。

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And that's when he began to explain his theory of "a thousand marbles".

接着他开始解释他的“1,000颗玻璃珠”理论。

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"And that's when he began to explain his theory of" a thousand marbles.

这时，他开始详细说明他那“一千颗弹珠”的理论。

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