I insisted __________ to see a doctor, but he insisted nothing __________ wrong with him.

A．on him to go; should be

B．he went; be

C．he go; was

D．he should go; is

（）是离子交换树脂的一个最重要的指标，它说明树脂的交换能力。

A.密度

B.含水率

C.交联度

D.交换容量