Problems with TP framework namespaces and use

as shown in the figure Email.php and Index.php are both namespaces namespace app\ index\ controller in the same directory. I wonder if I want to introduce this class file by using Email.php in Index.php. Why is it wrong for me to introduce use app\ index\ Email ?

Mar.14,2021

because under the same namespace, new Email is fine.

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b9e7cf-2f422.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b9e7cf-2f422.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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