- past perfect progressive of upgrade.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Last week, 38 North, a North Korea monitoring project affiliated with Washington’s Stimson Center think tank, said satellite imagery showed the North had been upgrading its Yongbyon nuclear complex.
From Reuters • Jul. 2, 2018
Workers had been upgrading science labs at the school.
From New York Times • Sep. 2, 2015