短语
中文翻译：在购买时
同义词：
['on the spot', 'on the ground例句：1. We need tobe on the buy when we go shopping.（我们需要在购物时保持警觉。）']
例句：
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1. We need tobe on the buy when we go shopping.
我们需要在购物时保持警觉。
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2. The store isclosed on Sundays, so you can't buy anything.
这家商店周日关门，所以你不能买任何东西。
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3. He wason the buy when hesaw the thief and calledthe police.
他看到小偷时立刻报警了。