We must do everything what we can water and paper.A. saveB. savingC. to saveD. saved

问题补充：

We must do everything what we can water and paper.

A. save

B. saving

C. to save

D. saved

答案：

A. save

B. saving

(答案→)C. to save

D. saved

解析：句意：我们必须做我们能做的一切来节约水和纸张。We must do everything what we can的目的是节约水和纸张，不定式做目的状语，故选C。