这几个句子有什么错?

hi:

One of their reasons is the old buildings have a long history.

改：
One of the reasons is that the old buildings have a long history.

Please write to me if you are convenient.

改:
Please write me if you are convenient.

May I borrow your phone?
正确！

Wearing traditional clothing is a way to remember our history and
culture, however, it is not an effective and prudent way.

正确！

is 后面要加that

把to 去掉

borrow 后面加介词with

最后一句实在想不出来，抱歉。

希望以上对你有所帮助！

One of their reasons is that the old buildings have a long history.
Please write to me if you are conveniece.
May I borrow your phones?
Wearing traditional clothings is a way to remember our history and culture, however, it is not an effective and prudent way.

1.在reasons is 后必须加that,因为句型是主语从句.
其他,我觉得,没啥错啊

我想说，楼上的改完后，都还是错的...
难道是错句改错吗？