由于离子交换树脂的（）不同，它们的酸碱性强弱也有差别。
A、离子
B、电离度
C、酸碱度
D、交换基团
参考答案：D
It is reported that some mainland visitors to Hong Kong Disneyland didn't ________ the park rules
and behaved improperly. [ ]
A. come up to
B. keep to
C. come about
D. make up
GK阀递动弹簧的自由高为（）。
A.34.5～35.5mm
B.41~45mm
C.31.5～34mm
D.65～68.5mm
