GRAMMAR. Read the sentences and choose the correct variant.
1. Baking soda is / is being a white crystalline powder (NaHCO 3 ) better known to
chemists as sodium bicarbonate.
2. At temperatures above 149 degrees Celsius baking soda is decomposing /
decomposes into sodium carbonate, water, and carbon dioxide.
3. The native chemical and physical properties of baking soda allow / allows to use
it in a wide range of applications, including cleaning, deodorizing, buffering, and
fire extinguishing.
4. People have started / started to use baking soda in air pollution control because
it absorbs sulfur dioxide and other acid gas emissions.
5. Baking soda has come / came from England and was first used in America
during colonial times.
6. In 1846, Austin Church, a Connecticut physician, and John Dwight, a farmer
from Massachusetts, had established / established a factory in New York to
manufacture baking soda.
7. At the second stage of making baking soda they put / has put the intermediate
soda ash solution into a centrifuge, which separates the liquid from the crystals.
8. The saturated sodium solution moved / had moved through the tower before they
have seen / saw that the centrifuge has been / was out of work.
9. Specialists usually manufacture / manufactured standard grades of sodium
bicarbonate to meet customers' specific requirements, and particle size is / are
the major determinant of grades.
10. Managers have agreed/ had agreed to buy a new carbonating tower before the
prices goes / went up.
How did people manage to domesticate a wolf? There are two hypotheses. First, people themselves took the initiative to tame a wild animal. The second version - in search of food, protection and new territory, wild wolves themselves came to people.
Dogs were the first animals to become companions and faithful helpers of people. As soon as primitive people discovered agriculture, they immediately started breeding dogs for various useful purposes. Dogs guarded dwellings and domestic cattle, helped hunters and shepherds. On cold nights a devoted four-legged friend warmed the owner with his body. Ancient excavations indicate that the dogs were buried with their owners.
Since ancient times, there have been many different breeds of dogs. To date, there are 337 canine breeds in the world.
I like dogs.