【简答题】
A、R-R<sub>0sub>=-k(T<sub>ysub>-T<sub>ssub>) B、R<sub>0sub>-R=-k(T<sub>ysub>-T<sub>ssub>) C、R-R<sub>0sub>=k(T<sub>ysub>-T<sub>ssub>) D、R+R<sub>0sub>=-k(T<sub>ysub>-T<sub>ssub>)