Extended katakana list
In this extended katakana chart, some of them have the same sounds but are used differently, such as ジ／ヂ (ji) and ジュ／ヂュ (ju). They are not interchangeable. Make sureャュョ (ya, yu, yo) on the left side of the chart are written smaller when you practice writing.
Here’s an optional table without Romaji - Extended katakana list without Romaji
Small ッ (tsu): Double consonants
This ッ (tsu) is smaller than the full size ツ (tsu). When there is a small ッ (tsu) between two katakana, you have to pause slightly between them when pronouncing it. Typing double consonants will produce small small ッ (tsu).
⁺vowel extender mark or long vowel mark:
a short line (ー) following the direction of the text, horizontal or vertical.
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English would seem more likely, I feel. The word was coined in Czech in 1921, but first attested in English only two years later in 1923 and quickly entered common usage. Unless there was some notable cultural or technological exchange between Japan and (then) Czechoslovakia during the first half of the 20th century (which, whilst not impossible, I have never heard of), it seems considerably less probable that the Japanese encountered the word through Czech. It would help to know when the first attestation in Japanese dates from.
The original usage of the word seems to be from Czech writer in R.U.R. https://en.wikipedia.org/wiki/R.U.R. But when the play was translated to Japanese, it was 「人造人間」 じんぞう にんげん (EN: Mechanoid, humanoid robot, android - not iPhone) in 1923. And another translated publication came out as 「ロボット」in 1924. By that time, the play premiered in NY and London. So I assume that the word ロボット is from English Robot, but the original creator of the EN word Robot is form Czech. (I'm only answering your questions based on the online resources available.)
You forgot ズ and ヅ.
There are dialects which maintain some or all distinctions and others that merge all four into a single sound.
Input methods maintain the distinctions out of morphological considerations.
Try typing Numazu and see if 沼津 comes up. If not, try
Numadu (ぬまづ ) instead.
Ditto for Awaji (淡路), another place name. If that fails, try the traditional