What really worries us is ______ the explorers can accurately locate themselves with the device in case of bad weather.
| A．that | B．where | C．what | D．whether |
Whenever I met her, _________ was fairly often, she greeted me with a sweet smile.
| A．who | B．which | C．when | D．that |
We are invited to a party _________in our club next Friday.
| A．to be held | B．held | C．being held | D．holding |
----John and I will celebrate our fortieth wedding anniversary next month.
-----Oh, _________!
| A．cheer up | B．well done | C．go ahead | D．congratulations |
