Had the boy worked harder, he ______ the exam.
The buses, ________ were already full, were surrounded by an angry crowd.
In many countries more and more forests and even agricultural land are being lost to development, _______ much of the land to become desert.
______ which school was suitable for their son, the parents visited lots of different primary schools in the city.
It was last Saturday ________ we visited the History Museum.
I'll go to the library as soon as I finish what I .