设 z = f(u, v),u = φ(x, y),v = ψ(x, y),则∂z/∂x = ( ) A、f'₁φ'₁+f'₂ψ'₁B、f'₁φ'₁-f'₂ψ'₁C、f'₁φ'₁+f'₂φ'₁D、f'₁ψ'₁-f'₂φ'₁ 发布时间:2025-10-02 22:19:19