葡萄是酸的用英语可以说成 "grapes are sour".
来源：葡萄中含有酸性物质，如果它们还未成熟，味道会很酸。
英文例句：
"I love eating grapes, but I don't pke it when they're too sour." (我喜欢吃葡萄，但是我不喜欢它们太酸了)
"I prefer sweeter grapes, but my sister pkes sour grapes." (我更喜欢甜葡萄，但是我姐姐喜欢酸葡萄)
"The grapes are still unripe and sour, we'll have to wait a bit longer for them to be ready to eat." (葡萄还没有成熟，味道很酸，我们还要再等一段时间才能吃)