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Question

1. The earth is the only planet with a large number of oxygen in its atmosphere.
            A                       B        C      D

2. Venus approaches the Earth more closely than any other planet is.
          A          B                       C         D

3. Robert Frost was not well known as a poet until he reached the forties.
                             A    B          C     D

4. The amounts of oxygen and nitrogen in the air almost always remain stable, but the amount of water vapor vary considerably.
        A                                    B                         C                  D

Answer 1

1. number ---> amount

2. is--->are

3. as--->for

4. vary--->varies