Explanation
Use "both" when you mean two things together. Use "either" when you mean one of two choices. Use "neither" when you mean not one and not the other.
For example, "You can choose either the window seat or the aisle seat." Here, "you can choose" gives the situation, "either" means one of two seats, and "or" shows the second choice. Japanese often says "窓側か通路側か" in one phrase, but English shows the choice with "either...or". In "Neither my brother nor my sister can drive," "neither...nor" means both people cannot drive, and the verb is usually singular after "neither".
"both" は「2つとも」という意味です。"either" は「2つのうちどちらか」です。"neither" は「どちらでもない、両方とも〜ない」です。
たとえば、"You can choose either the window seat or the aisle seat." では、"you can choose" が「選べる」という状況を表し、"either" が「2つのうち1つ」を示し、"or" がもう一方の選択肢を出しています。日本語では「窓側か通路側か」と一まとまりで言えますが、英語では "either...or" で選択をはっきり示します。"Neither my brother nor my sister can drive." では、"neither...nor" が「兄も妹も運転できない」という意味で、"neither" の後ろはふつう動詞が単数になります。
Examples
- Both of my parents are doctors. 両親は二人とも医者です。
- I brought both coffee and tea. コーヒーも紅茶も持ってきました。
- You can choose either the window seat or the aisle seat. 窓側の席か通路側の席、どちらかを選べます。
- Do you want either tea or coffee? 紅茶かコーヒー、どちらか欲しいですか？
- I don't like either option. 私はどちらの選択肢も好きではありません。
- Neither my brother nor my sister can drive. 兄も妹も運転できません。
Common Mistakes
Japanese learners often mix up the verb form. They say "Both of my parents is busy." or "Neither of them are late." In standard English, "both" takes a plural verb: "Both of my parents are busy." "Either" and "neither" usually take a singular verb: "Either of the options is fine." "Neither of them is late."
日本語では単数・複数の感覚が英語ほど強くないため、be動詞の形をまちがえやすいです。たとえば "Both of my parents is busy." は誤りで、正しくは "Both of my parents are busy." です。"either" と "neither" は、通常は単数扱いなので、"Either of the options is fine."、"Neither of them is late." のように言います。