come about
1．（of a ship or wind）change direction转向
It was so stormy that the ship had to come about and head for the harbour．风浪太大，船不得不调转航向，朝港口驶去。
2．happen；occur发生
How did it come about that the man is dismissed？那个人被解雇了，怎么回事？
The argument came about because they were talking about politics．争论是因为他们谈论到政治而引起的。