4.若从句叙述的是客观真理、自然现象或永恒不变的规律时,则不受主句时态的限制,仍用一般现在时。例如:
Our teacher told us light travels much faster than sound.老师告诉我们光传播的速度比声音快得多。
They knew the sun is much bigger than the earth then.他们那时就知道太阳比地球大得多,
He said that one and one makes two.他说一加一等于二。
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