Thomas Alva Edison didn’t “invent” the light bulb (灯泡), but rather he ______ a 50 –year –old idea, which is not well –known.
---Whose coat is here? ---_____.
After reading the text, he ___ down some words in his notebook.
---Could you tell me ___ all of you think of your teacher? ---She’s a good teacher.
All ___ can be done has been done.
The train __ for five minutes by the time we got there.