The economist claimed that the crisis and the suffering ______caused had a great influence on the whole world.

In societies where social roles are determined, boys usually copy the behavior of their fathers, and girls usually also copy _____ of their mothers.

In the past few years, a great many teachers have found       very important to teach their students how to learn.

I hate ___ when the weather in Changsha becomes freezing cold because there is no heater inside. 

-- Who is dancing to music in the next room?-- ________ the children.