The president of the USA        around the Palace Museum last month.

A．has showed

B．showed

C．was showed

D．has been showed

某黄土场地详勘资料如下表所示：场地中载荷试验圆形承压板面积为0.50m2，压力与浸水下沉量记录如下表，该场地中黄土的湿陷起始压力为（）。

A.50kPa

B.75kPa

C.85kPa

D.100kPa