The earth is our home . It well.A. must be protectedB. should protectC. need protectD. ne

问题补充：

The earth is our home . It well.

A. must be protected

B. should protect

C. need protect

D. need protecting

答案：

(答案→)A. must be protected

B. should protect

C. need protect

D. need protecting

解析：

试题分析: 句意：地球是我们的家。它必须被保护。must be protected必须被保护，should protect应该保护， need protect需要保护， need protecting需要保护；根据语境可知是地球被保护，故选A。