Fill in the blanks.

Scientists …………………… (have long been / are long been / were long been) speculating whether Mars has liquid water or not. The newest analysis, based on the sharpest pictures ever taken of the Red Planet, indicates that it …………………….. (didn’t / doesn’t / don’t).

The latest images come from a NASA spacecraft called Mars Reconnaissance Orbiter (MRO). The orbiter ……………….. (reach / reached / had reached) Mars last year. MRO recently ………………… (focuses / focused / has focused) its instruments on two steep gullies that scientists ………………… (have looked / had looked) at 15 months ago. At that time, researchers ……………………. (saw / have seen) deposits that formed bright streaks on the gullies. They ………………….. (suspect / suspected / had suspected) that a recent flow of salty water evaporated, leaving these streaks of minerals behind. But the newest data tell a different story. Scientists from the University of Arizona in Tucson ………………… (found / founded / find) no minerals in the deposits that would suggest the presence of water.

Answers

Scientists have long been speculating whether Mars has liquid water or not. The newest analysis, based on the sharpest pictures ever taken of the Red Planet, indicates that it doesn’t.

The latest images come from a NASA spacecraft called Mars Reconnaissance Orbiter (MRO). The orbiter reached Mars last year. MRO recently focused its instruments on two steep gullies that scientists had looked at 15 months ago. At that time, researchers saw deposits that formed bright streaks on the gullies. They suspected that a recent flow of salty water evaporated, leaving these streaks of minerals behind. But the newest data tell a different story. Scientists from the University of Arizona in Tucson found no minerals in the deposits that would suggest the presence of water.