The house is dirty because it since they moved out.
| A．doesn’t clean | B．isn’t cleaned |
| C．hasn’t cleaned | D．hasn’t been cleaned |
______ was not until the early 20th century _____ the importance of his ideas was realized.
| A．What; that | B．It; that | C．That; so | D．It ;when |
The on-line diary blog is a cultural _____, perhaps as essential as usual books we read.
| A．network | B．phenomenon | C．competition | D．occupation |
Jackie made _____ possible for this family to have beautiful memories during hard time.
| A．it | B．this | C．that | D．what |
Only after he realized the significance of mastering two languages ______ English carefully.
| A．did he set about learning | B．did he set out learning |
| C．had he set about learning | D．had he set out learning |
If you had arrived half an hour earlier, you _____ the well-known writer in the flesh.
| A．had met | B．would have met | C．would meet | D．could meet |