你的看法是对的!应该 slight growth,而不能用 slightly growth——原因很简单:修饰名词应用形容词,而不是副词。又如:
She has a slight fever. 她有点发热。
There’s a slight improvement in his condition. 他的情况略有改变。
Last year saw a slight increase in car accidents in that city. 该市去年车祸的次数略有上升。
比较下面用 slightly 的用法(修饰动词或形容词等):
I know her slightly. 我对她稍有了解。
Each of the houses is slightly different. 每座房子都稍有区别。