joshi.v123 wrote:Can any body please explain

Incorrect: The aliens WERE ARRIVED on Neptune in the 20th century. (Why this is Incorrect?)
Correct : The aliens ARRIVED on Neptune in the 20th century. (Why this is correct?)

Incorrect: After they advertised, sales WERE INCREASED by 25%. (Why this is Incorrect?)
Correct: After they advertised, sales INCREASED by 25%. (Why this is correct?)

HI Joshi,

Rule to note: A subject cannot have 2 verbs referring to it in the same clause.

The aliens WERE ARRIVED on Neptune in the 20th century.
in this sentence, WERE is a verb referring to aliens and ARRIVED is a verb again referring to Aliens.
Hence it is incorrect.

Same holds true for the other sentence.
sales were increased by 25%
WERE,INCREASED are both referring back to subject sales.
Hence incorrect.

Hope this helps!!

Tremendous differwnce in meaning. Lets look at this example:

After they advertised, sales WERE INCREASED by 25%

This indicates that advertising and increase in sales were independent events and does not show that sales increased because of advertising. were increased denotes an involuntary action.

Perhaps difference will be more apparent in the following:

He came to Bangalore (on his own).

He was brought to Bangalore (involuntary action).