你确定be about to有准备的意思吗？ 郎文词典：be about to do sth: if someone is about to do something, or if something is about to happen, they will do it or it will happen very soon. 可见，你的所有句子，真正的含义应该是： 我马上做作业。我正要做作业。 我马上打扫房间。我正要打扫房间。 …… 当然如果你觉得“准备”的意思也是我马上要做的什么的意思，那就没办法了。“准备”在汉语里，只是准备，并代表你一定会做，但be about to表达则是“即将做某事”，那事会很快被做。

Thank you, Dear friend!

The first three sentences are absolutely right!! And the fourth sentence “I'm about to read a newspaper” in Chinese it should be“我准备看报纸”. The subject of this sentence is“我” not“他”. And the last sentence,"I'm about to surf the internet" means“我准备去上网”. Hope my answer will help u.