For all his achievements,however,Halley's greatest contribut

For all his achievements,however,Halley's greatest contribution to human knowledge may simply have been to take part in a modest scientific wager with two other worthies of his day:Robert Hooke,who is perhaps best remembered now as the first person to describe a cell,and the great and stately Sir Christopher Wren,who was actually an astronomer first and an architect second,though that is not often generally remembered now.
his 在这里是什么结构?