For the past ten years we have been selling various durable goods to wholesalers and large retailers in all the major cities of China, and______a considerable number of well-established connections.

For the past ten years we have been selling various durable goods to wholesalers and large retailers in all the major cities of China, and______a considerable number of well-established connections.

A.has built

B.has built up

C.have built

D.have built up

正确答案是D