问题补充：
The number of people in the world about 6 billion and large quantities of waste each year.
A. total; has been produced
B. totals; is produced
C. totals; are produced
D. total; are being produced
答案：
A. total; has been produced
B. totals; is produced
(答案→)C. totals; are produced
D. total; are being produced
解析：可联系答.案.网客服索取。
