Although lectures supply us with many advantages ,there are still some defects which can't be neglect

Although lectures supply us with many advantages ,there are still some defects which can't be neglect
Although lectures supply us with many advantages ,there are still some defects which can't be neglect

Although lectures supply us with many advantages ,there are still some defects which can't be neglect
Although the lectures can bring some advantages to us,it also has some problems.

which前要逗号，非限制性定语
neglect要加ed表被动

貌似前后主语不太一致啊，你想表达什么意思。。。

除了neglect忘记用被动以外，我觉得都没错啊，which之前不需要加逗号啊，我之前写作文经常这样用，就是定语从句。