How about 25b? "This" is used as a pronoun -- but to what does it refer? Pollution? Population growth?
In 25a, "this" is used as an adjective. This sentence has no pronouns.
Which sentence is Vague pronoun
25a. Air pollution normally increases along with population growth. This increasing pollution is a big problem for many cities.
25b. Air pollution normally increases along with population growth. This is a big problem for many cities.
3 answers
Not understanding which sentence is verb form and verb tense.
9a. The ancient Egyptians built pyramids as burial sites for their leaders.
9b. The ancient Egyptians have built pyramids as burial sites for their leaders.
9a. The ancient Egyptians built pyramids as burial sites for their leaders.
9b. The ancient Egyptians have built pyramids as burial sites for their leaders.
Hereafter, please put up your own separate post....
Both of those are verb tenses.
"built" is simple past tense.
"have built" is a present perfect tense.
Check this site to see the sequence of tenses.
http://owl.english.purdue.edu/owl/resource/601/01/
Both of those are verb tenses.
"built" is simple past tense.
"have built" is a present perfect tense.
Check this site to see the sequence of tenses.
http://owl.english.purdue.edu/owl/resource/601/01/