6.Correct Answer: B
The word more requires a than. Attempting is correctly parallel to listening.
7.Correct Answer: C
After the preposition between the pro nouns should be in the object form and so we need me and not I. After doubt the simple future tense is correct.
8.Correct Answer: C
A semicolon is need to link two sentences. Of the choices with the semicolon, C is short and clear (and correct), D has merely in the wrong place, and E does not have a complete sentence after the semicolon.
9.Correct Answer: E
“Pollution and degradation” form a compound subject which needs a plural verb: are is correct.
10.Correct Answer: A
The construction not so much as... as is correct.