他没回来,butI am expecting him to arrive_ Aat any time Bat the time C at one time Dat this time

but I am expecting him to arrive at this time .我希望他现在就到来
at some/any/that time 未来不确定的某个时间
He is performing as well as at any time in his career.The UK has 500,000 stray dogs on its streets at any one time (=at any particular time) .
at a/the time when ...
At the time when this scheme was introduced,it was recognised that there might be problems.