82 Many writers find it harder and harder to ___ the radical changes of our time. (1 分)

A. come up with

B. keep up with

C. put up with

D. make up for

Many people simply say that they want something, but they do not ________ （花费，消耗

82.银行账户（ ）是指因利率水平、期限结构等要素发生不利变动，导致银行账户整体收益和经济价值遭受损失的风险。

化简：. 化简：.

测定铅锡合金中Pb、Sn含量时,称取试样0.2000g,用盐酸溶解后,准确加入50.00mL 0.03000mol/L的EDTA,50mL水,加热煮沸2min,

设随机变量X服从区间［0，1］上的均匀分布，Y服从参数为1的指数分布，且X与Y相互独立.求：（1）X及Y的概率密度；（2）（X，Y）的概率密度；（3）P｛X>Y