す可き[subeki] should do (abbr. of suru+beki)
可き[beki] should (suf. to verbs)
もし可能ならば[moshikanounaraba] if possible
可からず[bekarazu] must not
可愛がる[kawaigaru] to love

可愛らしい[kawairashii] lovely
可圧性[kaatsusei] compressibility
可換群[kakangun] Abelian group
可逆[kagyaku] reversible

アナログデジタル変換器[anarogudejitaruhenkanki] analog-digital converter
データ交換[deetakoukan] data exchange
パリティ変換[paritihenkan] parity transformation (physics)
メール交換[meerukoukan] exchange of letters
意見交換[ikenkoukan] exchange of ideas

引換て[hikikaete] on the contrary
下位互換性[kaigokansei] downward compatibility
かな漢字変換[kanakanjihenkan] kana-kanji conversion (on a computer, etc.)
可換群[kakangun] Abelian group
賀詞交換[gashikoukan] New Year greetings (parties)

悪循環[akujunkan] vicious circle
一環[ikkan] link (e.g. a part of a larger plan)
印環[inkan] signet ring (in medical contexts, e.g. signet ring cell)
円環[enkan] circle
花環[hanawa] wreath

環境[kankyou] environment
環境グループ[kankyouguruupu] environmental group
環境事業[kankyoujigyou] environmental business
環境庁[kankyouchou] Environment Agency
環境庁長官[kankyouchouchoukan] Director General of Environment Agency