這一天，小衝浪有一個新問題：“Daddy, is coal expensive or cheap?”

哇，娃開始關心價錢了，是個好事哈。老大我就說，“Coal is not expensive and can be cheap.”

“How can coal be cheap?”小衝浪的好奇心棒棒的。

“For some open-pit coal mines, the coal is just lying there on the ground, waiting for an excavator to dig it up and put it in a dump chuck. This way, the coal can be 'dirt cheap'.”老大我解釋。

“Oh, coal can be 'dirt cheap'.”小衝浪說，若有所悟。

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改天，小衝浪翻到他的一本書，上麵有講到一些biofuel，他很高興地跟我說，“Daddy, biochar is 'tree cheap'!”

我聽到了，想起來前些天聊'dirt cheap'來著，知道咱小衝浪又在練習舉反了，就表揚他說，“Good phrase - tree cheap!”

燃後，大小衝浪都很開心地笑了。

2024.5