57. 若使用 10:1 的探棒來測量某 V (t )=20sin (6280t+45°)的信號，則垂直電壓衰減選擇鈕(A.)與水準掃瞄時間選擇鈕(B.)應放置在何檔較為適當？(A)A=1V/div，B=0.2ms/div(B)A=2V/div，B=0.5ms/div(C)A= 2V/div，B=0.2ms/div(D)A=1V/div，B=0.5ms/div。