I think you should complain, _____, of course, you are happy with the way things are.
| A．until | B．although | C．when | D．unless |
—You were out when I dropped in at your house.
—Oh, I ________ for a friend from England at the airport.
| A．was waiting | B．had waited | C．am waiting | D．has waited |
It is said in the book that Thomas Edison (1847—1931) ________ the world-leading inventor for sixty years.
| A．would be | B．has been | C．had been | D．was |
Because the shop ________ , all the T-shirts are sold at half price.
| A．has closed down | B．closed down | C．is closing down | D．had closed down |
The discussion ________ alive when an interesting topic was brought in.
| A．was coming | B．had come | C．has come | D．came |
The teacher, with 6 girls and 8 boys of her class, ________ visiting a museum when the earthquake struck.
| A．was | B．were | C．had been | D．would be |