水中镁离子主要是由含CO2的水溶解了地层中的（）所致。
A.石灰石
B.石膏
C.白云石
参考答案：C
Mary was talking to me about her new dress.________，I was thinking about something else.[ ]
A．Meanwhile
B．Therefore
C．Besides
D．Otherwise
读下图回答下列问题。
判断该农场的农业地域类型，并说明理由。(6分)
