Snap Language

1. Economists have studied the possibility that a recession is inevitable. The results have shown (or show) that there is only a small change that the economy will continue getting worse in the last quarter of the current year.

(Although the study happened in the past, the present perfect these is used to report the findings. This makes the study and results “current,” that is, they are connected to the present.)

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Archaeologists have found an underground tunnel and hope it may lead to the long-lost tomb of Queen Cleopatra VII. They found part of the tunnel underwater and unearthed several artifacts, including coins that had Cleopatra’s name on them.

(As is common when reporting findings, the first sentence uses the present perfect tense, making the discovery about a current event. The other sentences are in the past tense to describe what they discovered &emdash; past tense. )

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The new training program has already benefitted employees tremendously. Managers report that their teams have become more confident in performing their duties.

(All verbs in this sentence are in the present — either the present simple or the present perfect. This makes the actions and results current.)

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Scientists with the Ecks Laboratory have developed a new way of disposing of plastic safely. They published their technique in the American Journal of the Environmentin May.

(The present perfect tense in the first sentence makes the news about the new technique current. The past simple must be used in the second sentence because it refers to something that happened “in May,” that is, in the past.)

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In the last few decades, research has shown repeatedly that poor eating habits and diabetes are closely related. For that reason, the federal government kicked off a national campaign last week to promote healthy eating.

(The first sentence refers to an action happening up to the present. The second sentence refers to an action that happened “last week,” that is, at a specific time in the past.)

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Since the United States put people on the Moon in 1969, NASA has prioritized missions to Earth orbit and to distant planets.

(The first part of the sentence puts the action in the past. The second part brings the action up to the present — that is, they still prioritize that today —, so the present perfect tense must be used.)

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How long have home computers been around?

(Home computers are still around. The question refers to a state that started in the past, but it comes up to the present.)

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People have known that the Earth is round for thousands of years.

(The expression “for thousands of years” shows the duration of something people started knowing in the past and still know today.)

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Although your writing has improved a great deal so far this semester, the score on last week’s written assignment was low because you made many careless mistakes.

(The “improving” is present and ongoing, so you need to use the present perfect tense. Making careless mistakes happened last week, thus in the past.)

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Since their town (be flooded) 30 years ago, the disaster (be) on the residents’ minds. Many people still remember vividly what (happen) to their homes and loved ones.

(The “flooding” happened in the past. It is still on people’s minds today, so you need the present perfect. What they still remember vividly happened in the past.)

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