我国有13亿人口,占全世界人口总数的22%;人均耕地面积为1.39亩,不足世界人均水平的()。
A.40%
B.50%
C.60%
参考答案:A
The petrol tank is empty. I _________it up before we left home.
A.had to fill
B.would have filled
C.should have filled
D.could have filled
简述CRM环境下企业业务流程面对的挑战。