Living in the country has its advantages, ____ freedom from pollution is the best.
| A．which | B．whose |
| C．from which | D．of which |
In that country, you can see the temple ___ the 12th century.
| A．dated from | B．dated back to | C．belonged to | D．dating from |
Only when I left my parents for Italy ___ how much I loved them.
| A．I realized | B．I had realized | C．had I realized | D．did I realize |
It was not until 1920 ___ regular radio broadcasts began.
| A．while | B．when | C．that | D．since |
The reason _____ he explained is ___ she was ill.
| A．that , that | B．which , that | C．why,because | D．why, that |
_______, the disease diphtheria would produce a powerful poison that would kill the paient.
| A．If untreated | B．If it untreated | C．To be untreated | D．If being untreated |