#include <stdio.h>
void main()
{
    float V1,V2,V3,V4,V5,V6,V7,V8,V9,V10,a,r1,p1,r2,p2,p;
    float Car,Har,Oar,Nar,Sar,Aar,Mar,V0,Vo2,V;
    printf("input Car=,Har=,Oar=,Nar=,Sar=,Aar=,Mar=,过量空气系数a=,p=\n");
    scanf ("%f,%f,%f,%f,%f,%f,%f,%f,%f\n",&Car,&Har,&Oar,&Nar,&Sar,&Aar,&Mar,&a,&p);
    Vo2=1.866*Car/100+5.56*Har/100+0.7*Sar/100-0.7*Oar/100;
    V0=Vo2/0.21;
    V=a*V0;
    V1=1.866*Car/100+0.7*Sar/100;
    V2=0.8*Nar/100+0.79*V0;
    V3=11.1*Har/100+1.24*Mar/100+0.0161*V0;
    V4=V1+V2;
    V5=V4+V3;
    V6=V2+0.79*(a-1)*V0;
    V7=0.21*(a-1)*V0;
    V8=V3+0.0161*(a-1)*V0;
    V9=V4+(a-1)*V0;
    v10=V8+V9;
    r1=V1/V10;
    p1=r1*p;
    r2=V8/V10;
    p2=r2*p;
    printf ("理论所需的氧气量=%f,理论所需的空气量=%f,实际所需空气量=%f
        烟气中Ro2的容积=%f,烟气中理论N2量=%f,烟气中理论水蒸气量=%f,烟气中理论干烟气量=%f,理论总烟气量=%f
        烟气中的实际N2量=%f,烟气中实际O2量=%f,烟气中实际水蒸汽量=%f,实际干烟气量=%f,实际总烟气量=%f
        三原子气体的容积份额=%f,三原子气体的分压力=%f,水蒸气的容积份额=%f,水蒸气的分压力=%f\n",
        Vo2,V0,V,V1,V2,V3,V4,V5,V6,V7,V8,V9,V10,r1,p1,r2,p2);
}
printf只打印一行吗？

任意行，可以用\n 作为打印换行，或者多个printf就行了

那你运行试试》。。斑竹