become的過去式和過去分詞形式是什么

　　He became very weak towards the end of his life.

　　他臨終時很虛弱。

　　What became of that student who used to live with you?

　　以前和你住在一起的那個學生后來怎么樣了？

　　It soon became apparent that no one was going to come.

　　很快就很清楚，沒人會來。

　　In the 1990s the area became a magnet for new investment.

　　這個地區在20世紀90年代成了新的投資熱點。

　　She only became coherent again two hours after the attack.

　　她發病兩小時之后才恢復了清楚地說話的能力。