Your advice was a great help to us, without which all our efforts .
| A．wouldn’t pay off | B．hadn’t paid off |
| C．wouldn’t have paid off | D．didn’t pay off |
One of the most important questions they had to consider was _________ of public health.
| A．what | B．this | C．which | D．that |
The computer was used in teaching. As a result, not only_________, but students became more interested in the lessons.
| A．saved was teachers’ energy | B．teachers’ energy was saved |
| C．was teachers’ energy saved | D．was saved teachers’ energy |
Scientists also have no idea how long it will be before all wild animals in the cages _____.
| A．should be set free | B．will be set free |
| C．are set free | D．would be set free |
She brought with her three friends, none of _________ I had ever met before.
| A．them | B．who | C．these | D．whom |
What do you mean, there are only ten tickets? There _________ be twelve.
| A．would | B．should | C．will | D．shall |