Complete the following sentences with the correct form of the verbs in parentheses.
- La acción de aprender ocurre desde el pasado hasta ahora, se usa present perfect: have learned.
- La segunda acción es una verdad general, presente simple: save.
I have learned in this project that electrolytes save people's lives.
- Last school year indica pasado simple negativo: did not do.
- During this one indica pasado simple afirmativo: did.
I did not do any experiment last school year; but I did a few during this one.
- Just con acción reciente se usa con present perfect: have just made.
Scientists have just made many discoveries on behalf of human beings.
- Primera acción reciente: have just told.
- Segunda acción negativa en presente simple: do not listen.
Scientists have just told us how to solve the climate change crisis but people do not listen carefully.
- Since I first subscribed marca inicio en pasado; la acción continúa: has arrived.
- El verbo en la cláusula con since va en pasado simple: subscribed.
My science magazine has arrived almost every week since I first subscribed.
- Acción con resultado presente y relevancia actual: have made.
With the help of technology, doctors and nurses have made significant steps in treating and preventing diseases.
- Estado general y permanente: presente simple are.
Reading
Individually, put the following steps to perform an experiment in order by writing the correct number on the line.
- Place a container for liquids, preferably transparent, of 500 ml.
- Measure 250 ml of water and 100 ml of edible oil.
- Add the liquids to the transparent container.
- Add a tablespoon of sand or soil.
- Mix the materials perfectly well.
- Wait until the elements are separated.
- Pour the upper liquid into another container until it separates from the lower liquid.
- Subsequently, pour the lower liquid into another container to separate it from the sand or earth sediments.
Respuesta: 1, 2, 3, 4, 5, 6, 7, 8.
The effects of technology on society are both positive and negative.
