His mother _____ teacher.
The British are not so familiar with different cultures and other ways of doing things, ________ is often the case in other countries.
________ some students are not aware of is ________ difficult life can be if they are not devoted to study.
________ you are supposed to do ________ you don't like a thing is change it. Don't complain.
His younger sister may already be in high school now, in ________ case this picture book is too childish for her.
It is by no means clear ________ the president can do something to end the strike.