Perhaps he's running with Tom.
這裏沒有任何語法錯誤，是正確的.
不用run，用running，be動詞後面一般加動詞的ing形式.
perhaps的解釋
ad. 也許，可能
perhaps的例句：
Perhaps I am wrong， but I think she is near forty.
也許我錯了，但是我想她快四十歲了。
Such a mistake would perhaps lead to disastrous consequences.
這樣一種錯誤可能導致災難性的後果
