PHP无法识别HTTP_GET

Question

我得到＆＃34; PHP致命错误：调用未定义的函数http_get（）＆＃34;

为什么PHP无法识别http_get（）;

    <?php 
$response = http_get("https://www.google.com/recaptcha/api/siteverify?", array(
  'headers' => array(
    'Accept' => 'application/json'
  )
), $info);

print_r($info);
?>