你好！妹妹在英语中可以翻译为 "sister"，这个词来自于古英语中的 "swuster"，其本意为 "女性兄弟"。如果你想用英语表达 "你说对了"，可以使用以下句子：
"You're right."（你说对了。）
"You've hit the nail on the head."（你说得很中肯。）
"You've got it."（你说得没错。）
例如：
A: "I think the capital of France is Paris." B: "Yes, you're right. Paris is the capital of France."（A: "我认为法国的首都是巴黎。" B: "是的，你说对了。巴黎是法国的首都。"）
A: "I think the answer to this math problem is 3." B: "You've hit the nail on the head. The answer is indeed 3."（A: "我认为这道数学题的答案是 3。" B: "你说得很中肯。的确是 3。"）
A: "I think the capital of Austrapa is Sydney." B: "You've got it. Sydney is the capital of Austrapa."（A: "我认为澳大利亚的首都是悉尼。" B: "你说得没错。悉尼是澳大利亚的首都。"）
希望这些信息对你有帮助！
"You're right."（你说对了。）
"You've hit the nail on the head."（你说得很中肯。）
"You've got it."（你说得没错。）
例如：
A: "I think the capital of France is Paris." B: "Yes, you're right. Paris is the capital of France."（A: "我认为法国的首都是巴黎。" B: "是的，你说对了。巴黎是法国的首都。"）
A: "I think the answer to this math problem is 3." B: "You've hit the nail on the head. The answer is indeed 3."（A: "我认为这道数学题的答案是 3。" B: "你说得很中肯。的确是 3。"）
A: "I think the capital of Austrapa is Sydney." B: "You've got it. Sydney is the capital of Austrapa."（A: "我认为澳大利亚的首都是悉尼。" B: "你说得没错。悉尼是澳大利亚的首都。"）
希望这些信息对你有帮助！