Someone is at the door. ________ must be Mr Smith.

One of the most important questions they had to consider was         of public health.

My mother often cooks _______ for us.

It’s very hard for Mary to work here, for ______ she does can’t satisfy her boss.

Confucius Constitute is a worldwide non-profit （非营利的）organization, _____ the Chinese government set up to popularize（推广）the teaching of Chinese and spread the Chinese culture.