A supply curve will always shift to the left due to excise taxes and fewer inputs.
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Excise Taxes: If the government imposes an excise tax on a good, the cost of production increases for suppliers. Higher production costs usually lead suppliers to offer less of the good at any given price, resulting in a leftward shift of the supply curve.
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Fewer Inputs: If there are fewer inputs available for production (e.g., raw materials, labor), the ability of producers to supply goods decreases, causing the supply curve to shift leftward.
On the other hand:
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Advances in Technology: This typically shifts the supply curve to the right, as technology improvements usually lead to lower production costs and increased supply.
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Future Expectations of Falling Prices: This can lead to a decrease in current supply as producers may hold back on selling their product in anticipation of better prices in the future, but it's not an absolute shift to the left under all circumstances.
In summary, the options that will always cause a supply curve to shift to the left are excise taxes and fewer inputs.