问题补充：
I don’t know .
A. what the population of Tianjin is
B. what is the population of Tianjin
C. how much the population in Tianjin is
D. how much is the population in Tianjin
答案：
(答案→)A. what the population of Tianjin is
B. what is the population of Tianjin
C. how much the population in Tianjin is
D. how much is the population in Tianjin
解析：宾语从句的结构：主语+谓语+连接词+从句。从句在句中作宾语。从句要用陈述句的语序。如果主句是一般现在时，从句根据需要选择时态，如果主句是过去时态，从句要用相应的过去时态。提问人口的总数用what.B语序错误，故选A
