a five per cent drop的用法和样例：
- But,if the order is for a large quantity,say,one thousand ton,we can give you a five per cent discount.
- A recent study found that a five per cent increase of birds in the skua diet would result in an annual loss of thousands of other seabirds.
- Watching the satisfied customer going out with a package under his arm, Mr. Lin suffered a pang with every dollar he took in, as the abacus in his mind clicked a five per cent loss off the cost price he had raised through sweat and blood.
- Here is your bill. We've added on the five per cent service charge.