Only when his mother died ________ how much he loved his mother.
Most of the Europeans refuse to accept GM food ______Americans regard it as the fruit from high tech.
Not only John and Tom but also their sister, Mary, ______great interest in the piano lessons.
—Shall I wait here for three hours? —Yes. Three hours ______for you to wait for such a doctor.
If nothing______, the oceans will turn into fish deserts.
The Philippines lies ______ the south of China, but Guangdong Province lies ______ the south of China.