I had a couple of questions from my students, and I would like to try to answer them.
1) Q:「都合（つごう）が 悪（わる）いです。= It's not convenient for me.」の「都合（つごう）」は なんですか。どのように 使（つか）いますか。= What is "tsugou" when using "tsugou ga warui desu."? And how we use it?
My Answer: 都合（つごう）is "convenience."
ex.1) 今日（きょう）は 都合（つごう）が 悪（わる）い。= It is not convenient [inconvenient] for me today.
ex.2) 都合（つごう）の よい時（とき）に 来（き）てください。= Come (to me) whenever you like [it suits you].
ex.3) いつが ご都合（つごう） よろしいですか？= When would be convenient for you?
2) Q:「おなかが すきました（Short form: すいた）」と「おなかが すいています（Short form: すいている）」の 違（ちが）い(= difference) は なんですか。 = What is the difference between "Onaka ga sukimashita (or suita)" and "Onaka ga suiteimasu (suiteiru)" ?
Vocabulary: おなか = stomach, すく = to become empty, すきました（or すいた）= became empty, すいています（or すいている）= is empty
My Answer: I think there is no big difference, but we more often use "おなかが すきました (or すいた) which literally means "my stomach became empty", when you would like to say "I'm hungry" in daily conversation. However when you would like to ask "Are you hungry?," we sometimes use "おなか すいてる?(or すいていますか?)" which literally means "is your stomach empty?"
3) Q: 「はじめる」と「はじまる」の 違（ちが）いは なんですか。= What is the difference between "Hajimeru" and "Hajimaru" ?
My Answer: One is transitive (-meru) and the other is intransitive (-maru). They are NOT interchangeable.
- I will start the class. = わたしは クラスを はじめます。Watashi wa kurasu o hajimemasu.
- The class will start. = クラスが はじまります。kurasu ga hajimarimasu.
Other example:
intransitive/transitive
- 変（か）わる / 変（か）える = change
- 止（と）まる / 止（と）める = stop
- 乗（の）る / 乗（の）せる = get on (the train, bus..) / load (something)
- 冷（ひ）える / 冷（ひ）やす = become cold / cool (something)
- 増（ふ）える / 増（ふ）やす = increase / enlarge
- 降（お）りる / 降（お）ろす = get off / unload (something)
- 落ちる / 落とす = fall down / drop (something)
- 壊れる / 壊す = get broken / break (something)
If you still have any question, please let me know!!
