of course 
一定，当然

例句：

1.Ben, of course, was the last to arrive. 

本当然是最后一个到的。

2.The great majority of players would, of course, sign the contract without hesitation. 

绝大多数运动员当然会毫不犹豫地签这份合同。

3.Of course, in the nature of things, and with a lot of drinking going on, people failed to notice. 

当然了，事出必然，酒酣之间人们没有注意到。