雖然我現在不算在學日文，可是曾經很想學 (也真學了一陣子)，所以當時對樓主這個問題也關注過。我打在下面的答案妳可以參考看看，若有錯誤也請 italki 的網友指正。 據我所知，日文 Ra 行子音的羅馬拼音之所以用了 R 而不用 L，是因為舌尖的起始位置比較接近代表捲舌音的 R，雖然最後聽覺上的結果比較接近 L。 L 音的發音方式是將舌尖放在上排牙的後面，然後放開；而日文的 R 是將舌尖往後拉，然後用舌尖快速「鞭打」硬顎 (上排牙後面那片隆起) 上方甚至後方，聽起來其實滿像西班牙文的 R。 L 音是將舌頭壓在上排牙的後方再徐徐放開，因為「徐」，所以和日文的 R 比起來，舌面保持直立的時間較久，於是和日文的 R 相比，L 音的起始口腔共鳴感較強 (理論上)。但日文的 R 聽起來終究是比較像 L 而不像英文的 R，所以以結果論，就如 nori 網友所說的，如果樓主不是完美主義者的話，用 L 的方式來唸也就可以了。 Not that I'm learning Japanese now, but I used to want to (and actually learned for a while), so I happened to have paid some attention to the same question during my learning. The following info is for your reference; you italki folks please by all means correct me if I am wrong. As far as I know, the reason why they use R instead of L for the consonant part in the Japanese Ra (ら) row is that the starting point of the consonant is closer to where English R is in your mouth, despite the fact that it sounds more like L. When you say an L sound, you place the tip of your tongue against the back of your upper front teeth and then release it. But when you say a Japanese R sound, you want to pull back you tongue and kind of “whip” it against your hard palate (the bump behind your upper teeth), which makes it sound very much like a Spanish R. Because the release of your tongue is relatively “slow” when you say an L sound, your tongue stays, comparing to a Japanese R, longer in a upright position. As a result, an L sound makes more resonance at the beginning, in contrast with a Japanese R sound (theoretically). After all, a Japanese R does sound more like an L instead of an English R, so you might as well, if you're not a perfectionist, do as nori said, and replace a Japanese R with an L sound, in terms of the final result.

Actually we don't distinguish 'ra' and 'la'.I think 'la' is more close to the right pronounciation 'ら'. 'Ra' and diffinitely different from 'ら', we don't roll our tongue when we pronounce 'ら'. 如果你是中国人的话，我想你可以用la的发音好一点，因为发音非常相似。 がんばってね～♪

The ra ri ru. . . are made almost exactly in between where you make the r and the l sound make your tongue like the l sound, but move your mouth like the r sound