帮忙看一下，这句句子有没有语法错误

我觉得对的.不过最好还是"I thought that",这样读起来顺口，但你的是没有错误的

我来回答一下吧,虽然我是读中文的.

I thought the pen didn't work because of its bad quality(质量).

分析:一般来说,这一句话是没有错误的.但是,严格上来说,它与平常上的英语作法有些出入.这里主要涉及到像think那样的动词.这一类的动词如果作为主句的谓语时,并且有一个宾语从句的话,那么我们要进行从句的否定时,我们只能通过否定主句的谓语动词think来否定从句.

如I don't think you are right.
而我们很少说,I think you aren't right.

所以,这一句最好改成这样:
I didn't think the pen worked because of its bad quality.

不对..
楼上也错了..
应为 I didn't think the pen worked because of its bad quality(质量).
楼上也错了,didn't后面的句子应也为过去式..

不对
因为think 的否定要前移到它的前面
应为 I didn't think the pen work because of its bad quality(质量).

否定前移也要看情况的！

楼上还有欠缺,提了"didn't",句子后面的动词应是原形,所以是 I didn't think the pen work because of its bad quality