現在進行形は単一行為だけでなく、反復・習慣の意味を表す場合もあります。単純形と比較した場合、単純形は永続的な習慣を、進行形は一時的な習慣を表します。以下の例では、青字部分からも、終了点が明白です。(3)では習慣が対比して用いられています。
(1) “I’m working at the Royal Clifton,” I told him. “You said you were working in Salisbury.” “Well, I’m not—not for another month.” “You're a porter at the Royal Clifton?” “No” “Make your mind up.” “I'm not working as a porter, I said, exasperated beyond caution. "I'm working as a doctor."――J Collee, A Paper Mask
(2) She is playing the piano every day. Her recital is bound to be success. (河上 1991)
(3) I don’t usually study English, but these days I'm studying it. I have an exam next month. (Confirmed by native speakers)
【References】
河上道生（1991）『英語参考書の誤りとその原因をつく』大修館書店