爆炸可能是由电路连接故障引起的。

The explosion ___may ___have been caused by a faulty electrical connection.

你遇到的可能不是迈克的兄弟——我想此刻他表弟正和他住在一起。

That ___may not ___have been Mike's brother you met - I think his cousin is staying with him at the moment.

海伦可能在你到达之前就已经离开了。

Helen ___may ___have already left by the time you arrive.