例句與造句

1. If the annuity is paid over a fixed period independent of any contingency, it is known as an " " annuity with period certain " ", or just " annuity certain "; if it is to continue for ever, it is called a " perpetuity "; and if in the latter case it is not to commence until after a term of years, it is called a " deferred perpetuity ".
2. It's difficult to find deferred perpetuity in a sentence. 用deferred perpetuity造句挺難的