echo数组单元的值不全
数组的为
array
(
[title] => 初一上册数学测试题
[id] => 6
[subject] => 14
[parts] => [[单选,100,1]]
[topic] => [[1,100]]
[json] => [[6,小红做一道数学题“ ';color:rgb(0,0,0);font-weight:bold;font-size:14px;font-family:
[#39;'>两个多项式 'font-family:times new roman'>a、b，b为，试求 'font-family:times new roman'>a b的值”。小红误将 'font-family:times new roman'>a b看成a－ ';color:rgb(0,0,0);font-size:14px;font-family:
[#39;'>b 'font-family:宋体'>，结果答案（计算正确）为．
'text-indent:21px;line-height:200%'>（ 'font-family:times new roman'>2）求出当x ';color:rgb(0,0,0);font-size:14px;font-family:
[#39;'>] => 3时a b的值.
,1,100]]
[total] => 100
)

我在打印其中的json键时，却没打印全，显示
[[6,?6[subject]?=>?14[parts]?=>?[[单选...' data-pics=>
------解决方案--------------------
请输出var_export($arr)结构;