(7分)
&nBsp&nBsp&nBsp&nBsp某同学用量程为1mA、内阻为120ω 的表头按图(A)所示电路改装成量程分别为1v和1A的多用电表。图中r₁和r₂为定值电阻，s为开关。回答下列问题:
&nBsp&nBsp&nBsp&nBsp&nBsp&nBsp&nBsp&nBsp
表笔A应为________色(填“红”或“黑”)。