单项选择题 What is a perpetuity? A、A perpetuity is a final annuity whose period is infinite. There is no future value for perpetuity. B、A perpetuity is an annuity whose period is infinite. There is no future value for perpetuity. C、A perpetuity is a final annuity whose period is infinite. There is no present value for perpetuity. D、A perpetuity is an annuity whose period is infinite. There is no present value for perpetuity.
判断题 灯光投射的方位包括灯具安装的文职、投光方向及角度。
单项选择题 在PS中按住那两个键可中心()等比( )缩放。 A. shift Ctrl B. shift Alt C. ctrl alt D. shift shift