PREP 07 5 疑问

弥小岛

The airline company, following through onrecent warnings that it might start reducing service,

announced that it was eliminating jetservice to nine cities, closing some unneeded operations,

and it grounded twenty-two planes.

(A) closing some unneeded operations, andit grounded

(B) closing some unneeded operations, and grounding

(C) was closing some unneeded operations,while it grounded

(D) it closed some unneeded operationsand grounded

(E) it was closing some unneededoperations, and grounding  

OA:B

有一个疑问是最后一个and前为什么有个逗号，不应该是A,B AND C的结构吗？另外ground plane是停飞飞机的意思？

alzn2765

A, B, and C
ground plane的意思你觉得查字典不能解决吗？