So, if I may make a suggestion, please keep your exchange memo safe.
那么，如果我可以提一个建议的话，请您保管好这张兑换水单。
Need I leave my phone number?
需要我留个电话吗？
You can draw on this account by cheque in payment of goods.
您可以用支票提取存款来偿付购物的费用。
I most certainly can.
我当然可以。
Please sign on the top line.
请在头一行签名。