Ling Ming and I am at the park.对吗?

Ling Ming and I am at the park. 不对。人称数不符合习惯用法与语法。应当是：“Ling Ming and I are at the park.”（先不考虑时态）。

不对。
Ling Ming and I are (were) at the park.

不太好吧。
语法上也可以

It is wrong.Ling Ming and I are at the park.

你把am改成are就可以了。