. I just don't understand_____________ that prevents so many Americans from being as happy as one might expect.
| A．why it does | B．what it does |
| C．what it is | D．why it is |
The singers _____ from the whole country are expected to bring us a wonderful performance this weekend.
| A．selecting | B．selected | C．having been selected | D．to select |
_____ the government recovers the vehicle purchase tax and the oil prices go up continuously, the sales of the vehicle in China are still increasing every year.
| A．When | B．Once | C．Since | D．While |
After the flooding, people were suffering in that area, _____ urgently needed clean water, medicine and shelter to survive.
| A．who | B．where | C．which | D．that |
-- Why didn’t you go to Mike’s birthday party yesterday?
-- Well, I _____, but I forgot it.
| A．should | B．would | C．should have | D．must have |
It is not how much we do but how much love we put into what we do _____ benefits our work most.
| A．when | B．that | C．what | D．how |