Question

The quality of products __________ over time. A) are degrading B) have been degrading C) have degrading D) were degraded​

Answer 1

Answer:

YOUR ANSWER IS

OPTION

(D) WERE DEGRADED ..

Answer 2

The quality of products has been degrading over time.

Explanation:

• Here present perfect tense with the verb "has" is used because we are talking about the quality(singular).
• As the quality is degrading and has degraded over time which means that this process has started in the past and still continues so we have used the present perfect tense.
• is degrading which is present continuous tense would have been used only if the action is going on and no past is mentioned. For example- The boys are playing.

           Here, the time from which boys are playing is not mentioned so playing is used. But present perfect tense for this sentence will be used if the sentence is "The boys have been playing for a couple of hours."

[Your question is improper but most probably you meant-

The quality of products _______over time. A)is degrading B)has been degrading C)has degrading D)was degraded.]