The research lacks evidence, and therefore, its conclusions are doubtful.
| A．solid | B．fierce | C．severe | D．potential |
Only when I woke up______ what had happened.
| A．I knew | B．I did know |
| C．did I know | D．had I known |
The weather turned out to be very good, _________ was more than we expected.
| A．which | B．what | C．that | D．this |
Look out! Don’t get too close to the house _________ roof is under repair.
| A．which | B．whose |
| C．of which | D．of that |
The English play _________ many students are preparing at the New Year’s party will be a great success.
| A．for which | B．at which |
| C．in which | D．on which |
There was a time _____Soapy had to beg from door to door to make himself alive.
| A．when | B．that | C．while | D．how |