What does the word “these” refer to?

Let’s watch new that DVD you bought today, _______?

______ are substances or waste materials that are harmful to the environment and human.

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions
My sister and I’m never allowed to chew gum when we were young.

                         A                                          B             C      D

I won’t give you a test_________.

Although a deal has been agreed, it is not yet ________.

Mark the letter A, B, C, or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) OPPOSITE in meaning to the underlined word(s) in each of the following questions. 
Good communicators can speak and write clearly and succinctly.

Learning means acquiring knowledge or developing the ability to perform new _______.

What can be inferred from the last paragraph?

The last time I met him was 5 years ago.

According to the passage, all of the followings are true EXCEPT __________.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

Peter didn’t prepare well for his interview. As a result, he failed it.

The professor's lecture on quantum physics was disrupted by the continual interruptions

A                      B

from the rowdy students, which made it difficult for the other attendees to fully comprehend the 

        C             D

complex concepts.