_____ life exists on any other planet in the solar system still remains a question.
| A．Why | B．Whether | C．How | D．Where |
27．After the adventure, the children returned home, ______.
| A．safe but tired | B．safely but tiredly |
| C．safely but tired | D．safe but tiredly |
26．— Do you have any idea what Paul does all day?
— As I know, he spends at least as much time playing as he ______.
| A．writes | B．is writing | C．does writing | D．does write |
25．The peace talks between the two countries have ______. No agreement was reached.
| A．been broken down | B．broken down |
| C．been breaking down | D．been broken up |
24. ______is known to all, the Amber Room belongs to the Russians.
| A．As | B．Which | C．That | D．What |
23. Please remain _____until the plane has come to complete shop.
| A．to seat | B．to be seated | C．seating | D．Seated |