again 的地方

They had just had enough time to swim out of danger when the boat again completed a circle. 这句话为何是again completed，不应该是completed a circle again吗？again修饰动词不是放后面吗？

again 并不是像你理解的那样只能放在句末。again 可以坐落于句首，句中。只是最常见的是坐落于句末。比如：

I visited Beijing again. 普通说法。

Again I visited Beijing. 强调again。

I again visited Beijing. 强调Beijing，again坐落于主谓之间。