qt程序运行时的错误？undefined reference to `_imp___ZN10QTcpSocketD1Ev'



出现的错误为：
undefined reference to `_imp___ZN10QTcpSocketD1Ev'
undefined reference to `_imp___ZN10QTcpSocketC1EP7QObject'
undefined reference to `_imp___ZN10QTcpSocketD1Ev'
undefined reference to `_imp___ZN10QTcpSocketD1Ev'
undefined reference to `_imp___ZN10QTcpSocketD1Ev'
undefined reference to `_imp___ZN10QTcpSocketD1Ev'
undefined reference to `_imp___ZN10QTcpSocketD1Ev'
undefined reference to `_imp___ZN15QAbstractSocket13connectToHostERK7QStringt6QFlagsIN9QIODevice12OpenModeFlagEE'
undefined reference to `_imp___ZN15QAbstractSocket5closeEv'

collect2: ld returned 1 exit status

解决方案：

貌似链接错误。检查.pro文件中是否缺少
 QT += network