I phoned Sarah last night, ______ there was no answer.
| A．and | B．but | C．or | D．so |
I always go skiing with my friends ______ winter.
| A．in | B．on | C．at | D．for |
The students are talking about ______ holiday plans happily.
| A．his | B．her | C．its | D．their |
Nobody knows ______ yesterday.
| A．how the accident happens |
| B．how does the accident happen |
| C．how the accident happened |
| D．how did the accident happen |
The park gates ______ at 10:00 every evening.
| A．lock | B．locked | C．are locked | D．were locked |