The project to clear up the polluted river()by the end of next yearA is being completed B has been completed C will have been completed D will have completed

问题描述:

The project to clear up the polluted river()by the end of next year
A is being completed B has been completed C will have been completed D will have completed

c

C,将来完成时的被动式.BY+将来时间,是很典型的将来完成时标志.