求问in/hand,at/hand,on/hand各是什么意思?

即将到来He believes that the great day is at hand。他相信这个伟大的日子就要到来。in hand在手头的I have enough data in hand。我手上有足够的资料。被控制住The situation is now in hand。局势已经控制住了。在进行中The printing of the book is now in hand。这本书正在付印中。on hand在手头,在近处There weren't enough snacks on hand for the party。现有宴会的点心不够用。We have nobody on hand to repair your car。我们现在没有人能修你的车。I always like to keep a certain amount of money on hand。我总喜欢在手头备好一笔钱。出席,在场clasp sb。by the hand紧握某人的手He clasped his old friend by the hand。他紧紧地握住老朋友的手。