用a rate还是rates

在论文中想用 respectively 同时表达两个速率:
我的意见用：“with the rate of 40% and 50% respectively”！
它只表示单个速率，有‘respectively’代表人称数。另外将‘a’改为‘the’。

rate 英[reɪt] 美[ret]
n. 速度; 比率; 等级; （利息等的） 费率;
vt. 估价; 值得; 责骂; 定级;
vt.& vi. 认为，把…算作;
全部释义>>
[例句]The rate at which hair grows can be agonisingly slow.
头发生长的速度可能极其缓慢。
更多例句>>
复数：rates 过去式：rated 现在分词：rating 过去分词：rated第三人称单数：rates

With the use of "and" between the two rates, you always use plural form "rates" in this case. The adv. respectively only means "in the order given" or sequentially, which doesn't change the fact we are still talking about 2 rates. That is, the correct expression should be

With rates of 40% and 50% respectively

Or better, put a comma in between, to say

With rates of 40% and 50%, respectively

一致性原则 用第一个