Question: Once you have done so it is time to check the connecting cables
Please fix the punctuation.
Fixed: [Once you have done so, it is time to check the connecting cables.]

Question: There are often complains of chemicals getting mixed up with one another during the time of transportation and delivery
Please fix the punctuation.
Fixed: [There are often complains of chemicals getting mixed up with one another during the time of transportation and delivery .]

Question: Frequency to 200 kHz and duty cycle
Please fix the punctuation.
Fixed: [Frequency to 200 kHz and % duty cycle]

Question: When one of the great business leaders preaches customer centricity it is music to our ears it confirms that it pays to think about the customer first in order to achieve success Here is an excerpt from the article Richard Branson on the Secret to Exceeding Customer Expectations from entrepreneurcom
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Fixed:
[When one of the great business leaders preaches customer centricity , it is music to our ears - it confirms that it pays to think about the customer first in order to achieve success. Here is an excerpt from the article "Richard Branson on the Secret to Exceeding Customer Expectations" from entrepreneur.com.]