纯水制备常用电渗析法、离子交换法、（）法三种。
参考答案：蒸馏
D／A方式下既可以使用即期汇票也可以使用远期汇票，但只能是商业汇票。
The man insisted _____ a taxi for me even though I told him I lived nearby. [ ]
A. find
B. to find
C. on finding
D. in finding
