Well, the thing is that, the congestion charges, they were introduced first as a trial, so they were introduced in January and then abolished again at the end of July, followed by a referendum, and then they were reintroduced again in 2007, which of course was a wonderful scientific opportunity.
事情是这样的，交通拥堵费， 一开始是试验性质的， 一月份开始推广，七月底在一次公投后取消了， 在2007年再度收取， 这当然是一次难得的科学实验的机会。