Only when David did it a second time _________.
| A．he realized his mistake |
| B．he was realizing his mistake |
| C．did he realize his mistake |
| D．he did realize his mistake |
Experts think that ________ recently discovered painting may be ________ Picasso.
| A．the；/ | B．a；the | C．a；/ | D．the；a |
On ________ Friday when Tom was having an art lesson，as he had no color pencils with him，he drew ________ blue sun with his pen.
| A．/；the | B．/；a | C．the；the | D．a；a |
—Who called me this morning?
—________ Mr.Li.He asked you to visit Shenzhen and said that ________ Shenzhen today is different from what you saw thirty years ago.
| A．/；/ | B．A；/ | C．/；the | D．A；the |
What ________ surprise to see you here!
| A．the | B．/ | C．a | D．an |
________ walk is expected to last all day，so bring ________ packed lunch.
| A．A；a | B．The；/ | C．The；a | D．A；/ |