關於php中的switch語句 報錯

switch($rank)        {            case 1:                $speed = 50;            break;            case 2:                $speed = 48;            break;            case 3:                $speed = 46;            break;            case 4:                $speed = 44;            break;            case 5:                $speed = 42;            break;            case 6:                $speed = 40;            break;            case 7:                $speed = 39;            break;            case 8:                $speed = 38;            break;            case 9:                $speed = 37;            break;            case 10:                $speed = 36;            break;            case 21 > '$rand' >10:                $speed = 35;            break;            case 31 > '$rand' > 20:                $speed = 34;            break;            case 41 > '$rand' > 30:                $speed = 32;            break;            case 71 > '$rand' > 50:                $speed = 31;            break;            case 101 > '$rand' > 70:                $speed = 30;            break;            case 201 > '$rand' > 100:                $speed = 29;            break;            case 301 > '$rand' > 200:                $speed = 28;            break;            case 401 > '$rand' > 300:                $speed = 27;            break;            case 501 > '$rand' > 400:                $speed = 26;            break;}

在啟動並執行時候報錯>符號有誤 這是什麼情況啊

