---You look unhappy, what’s happening, my son?
---I’m wondering how long it’ll be________ we come to China again.
| A．since | B．when | C．before | D．after |
As is announced in the newspaper, the 20th World Cup __________ in 2014 in Brazil between June and July.
| A．is held | B．will be held | C．will hold | D．will be holding |
The buses, ________ were already full, were surrounded by an angry crowd.
| A．most of them | B．which most |
| C．most of which | D．that most |
In many countries more and more forests and even agricultural land are being lost to development, _______ much of the land to become desert.
| A．caused | B．causing | C．having caused | D．to cause |
______ which school was suitable for their son, the parents visited lots of different primary schools in the city.
| A．To find | B．Being found | C．Found | D．Finding |
It was last Saturday ________ we visited the History Museum.
| A．which | B．and | C．that | D．Where |