31．_________reasonable, the idea he to create a friendly environment attracted much public attention.
| A．Sounded; came about | B．Sounded; came across |
| C．Sounding; came up with | D．Sounding; came along |
_____more countries can use natural energy in the future remains to be seen.
| A．Whether | B．This | C．who | D．If |
It worried her a bit _____her hair was turning gray.
| A．while | B．if | C．that | D．for |
.____the meeting should last two days or three days doesn’t matter.
| A．That | B．Whether | C．If | D．Where |
Is _____he said really true?
| A．that | B． what | C．why | D．whether |
The question came up at the meeting_____ we had enough money for our research.
| A．that | B．which | C．whether | D．if |