Verb tense, form, and consistency — ACT practice questions

Hydrologist Celia Mendez wanted to learn where rainwater traveled after disappearing into a gravel basin beside a community garden. During a dry week, her team installed clear sampling tubes at three points downhill. Each morning, Mendez checks¹ the water level in every tube and recorded the result on a field map. The first readings revealed one problem, the underground water moved too slowly to trace by level alone.²

Mendez therefore mixed a harmless fluorescent dye into a measured bucket of water. The team poured the mixture into the basin at nine o'clock and covered the opening so another shower could not dilute it. By noon, the dye concentration in the lowest tube had risen³ from zero to four parts per billion. Mendez compared two channels, one ran beneath compact clay, and the other crossed loose gravel.⁴ The gravel channel carried the brighter sample, suggesting that its larger spaces allowed faster movement. Team members photographed each tube against a white card so faint color changes could be compared later.

After an overnight storm had ended, Mendez repeats⁵ the test with fresh dye. The crew needed three supplies: sealed vials, numbered flags, and a stopwatch.⁶ This time, water entered the basin at a steadier rate. Before the lowest probe sent its signal, the tracer had went⁷ beyond the middle tube. The surface looked calm, however, the probe recorded a rapid current below.⁸ Mendez checked the electronic reading against a vial collected by hand, and both measurements showed the same dye concentration. The crew sealed each vial immediately and wrote its collection time beside the corresponding flag number.

The path of the tracer helped the garden committee choose a safer location for a storage shed. Mendez knew that if the gravel channel continued at the measured rate, runoff would reach⁹ the proposed foundation during a long storm. The final map changed the committee's plan, members moved the shed ten meters east.¹⁰ The new site stood over compact soil, where both rounds of testing had shown slower underground movement. The committee also kept the flagged sampling tubes in place so future volunteers could compare water levels after unusually heavy rain.