I seem to have mislaid my keys.

我好像不知道把钥匙放在哪儿了。

I appear to have mislaid my sweater.

我好像忘了把毛衣放哪儿了。

I mislaid my English textbook.

我不知把英语课本丢在哪儿了。

Perhaps I have only mislaid it.

也许只是我放失了手。

Perhaps Ihave only mislaid it.

或许，我仅仅错置了它的位置。