Many people like to work by hand, but machines can do numerous great jobs better than humans. In my opinion, working with machines has several advantages, such as: safety, neatness, and quickness. Machines
have offered several jobs perform several functions that are impossible for human to do.
If you use a noun in singular you must put an article - definite or indefinite depending on the circumstances - before the countable ones. Otherwise, use such nouns in plural.
First, when people work by hand, the risk of damage is very high. If they don't pay attention carefully during work, parts of body are gone.
It is true regarding machines as well. People engaged in occupations that involve operation of machines should be even more careful, since machines due to their parameters can be especially dangerous to people. This assertion can be supported with numerous facts from newspapers and by reports about industrial accidents.
For example, a long time ago, employees of canneries worked by hand. It was actually very common that the employees lost their hands, and other parts of body.
how did it happen? include more facts to show the relation between working in canneries and injuries.
Eventually, machines were introduced to the canneries, and - no need for comma here - the number of injuried people began to decrease.
show the source - refer to some statistics or surveys - to prove that your example is not mere an allegation. It is not necessary to state the name of the source; just mention in general, like 'surveys say' or 'statistical agencies assert'.
Second, people can get tired and bored
, or other conditions that affect their work, whereas machine cannot. When machines are used, they will produce the same products without any damage. On contrary, no one can make two identical products by hand. There must be a different, in shape, condition, size, etc.
- I do not understand what you imply to in this paragraph. Your sentences are incoherent; your statements are vague. The overall paragraph lacks fluidity of ideas.
In conclusion, machines have many great features that are impossible for human to compete
best of luck!