PHP致命错误:PHP 5.5中找不到类'Curl'

我正在尝试运行此代码:

 'graphicdesign', "key" => "W*i*e*V*M*N*F*y*b*t*R*((", "filter" => "!2.5sIHWRkCVWC)rFPY_1P", "order" => "desc", "sort" => "creation");

    $httpresponse = (new Curl)->exec($url . '?' . http_build_query($data), [CURLOPT_ENCODING => 'gzip']); //Line 6

    $obj = json_decode($httpresponse);
    $response = $obj->{'items'};

但是,它失败并出现此错误:

$ php getcomments.php 
PHP Fatal error:  Class 'Curl' not found in /home/me/gdcommentgetter/getcomments.php on line 6

从我之前的问题,我可能是我的PHP版本的问题 - 实例化的类成员访问在((new Object)->method()) PHP 5.4之前是不可用的.

php --version但是,显示我的版本> 5.4:

$ php --version
PHP 5.5.7-1+sury.org~precise+1 (cli) (built: Dec 12 2013 21:48:51) 
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2013 Zend Technologies
    with Zend OPcache v7.0.3-dev, Copyright (c) 1999-2013, by Zend Technologies

我sudo apt-get install php5-curl按照许多地方的建议运行,但它仍然失败并出现同样的错误.怎么了？