客户收到语音短信并已收听，但没有进行保存，系统可以保存多长时间？
参考答案：客户收听留言后除非选择保存留言，否则系统将自动删除该语音短信（系统保存1天）
.
Many scientists believe that now we can study the behavior of a three-year-old child to see ____ they
will grow up to be criminals.
A．that
B．how
C．why
D．whether
海上钻井平台有哪几种类型？
