As is known to all Montreal is the second largest French-speaking city in the world .A.

问题补充：

As is known to all, Montreal is the second largest French-speaking city in the world, .

A. Paris is the largest

B. Paris being the largest

C. Paris to be the largest

D. Paris be the largest

答案：

A. Paris is the largest

(答案→)B. Paris being the largest

C. Paris to be the largest

D. Paris be the largest

解析：考查独立主格结构。句意：众所周知，蒙特利尔是世界上说法语的第二大城市，巴黎是最大的（城市）。横线前有逗号，前后是两个分句，前后分句应该用and/but连接，排除A；Paris和be是主谓关系，应该使用现在分词表伴随状况，排除C；D项不能使用原形be作谓语，排除D，故选B。