It was not until the subprime loan crisis（次贷危机） ____ great damage to the American financial system that Americans ____ the severity of the situation．
| A．caused, realized | B．had caused, realized |
| C．caused, had realized | D．was causing, had realized |
With a lot of problems ________, the newly – elected headmaster is having a hard time.
| A．settled | B．settling | C．to settle | D．being settled |
Soon after getting off his horse, the man appeared at the second storey windows, ___________he could see nothing but trees.
| A．from which | B．from where | C．in where | D．which |
Tom was very angry about ________ to Mary’s birthday party.
| A．not inviting | B．being not invited | C．not being invited | D．not to be invited |
You can come here to ask me _____ if you have any questions.
| A．at one time | B．at your time | C．at any time | D．all the time |
Having a trip abroad is certainly good for the old couple, but it remains ______ whether they will enjoy it.
| A．to see | B．to be seen | C．seeing | D．see |