はいり

わたしは まいばん おふろ に はいり ます。

The correct answer is `はいり` (hairi). This is the stem of the verb `はいる` (to enter, to take a bath/shower). It correctly combines with `ます` to form `はいります` (take a bath - polite present tense). The particle `に` correctly marks `おふろ` (bath) as the destination. So, `おふろにはいります` means "take a bath." `おふろ` is the noun and should precede `に`. `に` is the particle and should precede the verb stem. `ます` is the polite ending and should follow `はいり`. *Grammar Tip:* The phrase `おふろにはいります` (to take a bath) is a common collocation. The particle `に` is often used with verbs like `はいる` to indicate a destination.

正解(せいかい)は「はいり」。「はいる」語幹(ごかん)で「はいります」完成(かんせい)。「おふろに」で「入(い)る」。「おふろ」は名詞(めいし)。「に」は助詞(じょし)。「ます」は語尾(ごび)。 文法(ぶんぽう)：「お風呂(ふろ)に入(はい)ります」で「お風呂(ふろ)に入(はい)る」。