The part of the sentence "made some improvements" is correct and usable in written English. You could use this phrase when you want to describe a situation in which something was changed for the better. For example: "The company has made some improvements to their products, resulting in better customer satisfaction.".
They made some improvements.
"They've made some improvements," he said.
Eudoxus's successor Callippus made some improvements to the model.
Mr. Hesse has made some improvements during his tenure.
Mr. D'Ambrosio made some improvements to stores that analysts applauded.
"Brian made some improvement," Fassel said.
"As a result we have made some improvement.
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Ha Thuy Vy
MA of Applied Linguistic, Maquarie University, Australia