We’ve spent a lot of time looking at what’s inside a cell. What, then, is on the outside? It depends a lot on what kind of cell you’re looking at.
https://www.khanacademy.org/science/biology/structure-of-a-cell/cytoskeleton-junctions-and-extracellular-structures/a/the-extracellular-matrix-and-cell-wall
Why have they used present perfect "we have spent " and not "we have been spending"?
Jigneshbharati Why have they used present perfect "we have spent " and not "we have been spending"? The spending has finished.
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JigneshbharatiWhy have they used present perfect "we have spent " and not "we have been spending"?
The spending has finished.