—Who is the baby in this photo?—It’s my sister’s son. The photo _____ by her by e-mail ten days ago.

Mary isn’t ________ a book.  She is ________ TV. 

Robots _____more heavy work for us in the future.

---How dangerous! --- Yes. I think the policeman should stop the children      soccer in the street.

--- Where is your mother?--- She _______ to Sichuan on business. She has ______ there four times recently.