互换交易涉及的因素包括（）。
A.交换者
B.金额
C.期限
D.货币
参考答案：A, B, C, D
小园栽鲜花32朵，小艳栽鲜花57朵，以后小园每天栽4朵，小艳每天栽9朵，几天后小艳有的鲜花数是小园的2倍（用方程解）？
Tom is good at his work, but he seems to _____ confidence.
A lack B lack of C lacking in D short of
