单项选择题A．oxygen.B．ancient weather.C．carbon dioxide.D．temperature.

填空题live as — 改成like

填空题in average — 改成on

填空题supplementing — 改成supplemented

单项选择题A．negotiating about photographic material.B．negotiating an automobile agreement.C．facing serious problems in trade.D．on the verge of a large-scale trade war.