两道AS WITH 的题，求解

ving88

1.As virtually all the nation's 50 busiest airports are, New Youk's were built for an age of propellers, before jut planes weighing 800,000 pounds needed over two miles of runaway.
B  As with virtually all of the nation's 60 businest airports  
答案是A

2.
As it is with traditional pharmacies, online drugstores rely on prescriptions to be successful, since it is primarily prescriptions that attract the customers, who then also buy other health-related items.
A.As it is with traditional pharmacies, online drugstores rely on prescriptions to be successful

B.As with the case of traditional pharmacies, online drugstores rely on prescriptions to have success

C.As is the case with traditional pharmacies, prescriptions are the cornerstone of a successful online drugstore

答案为什么选B

ving88