I am very interesting in problems caused by pollution.

        A                   B                                C               D

The first national park in the world, calling Yellowstone Park, was established in 1872.

        A                               B                      C                                                 D

The package must be wrapped carefully before it is post.

                 A                     B                                C           D

It was such a difficult homework that it took me two hours to finish it.

            A          B                                  C                                           D

Of all the portraits he has painted, I like this one more.

    A                                         B             C                   D

The teacher asked him why hadn't he done his homework, but he said nothing.

                                              A              B                                     C              D

They hardly never go to the beach because of their thickness, do they?

                          A                        B              C                                       D

By the time I had found the key, I hadn't got into the house even heavy rain.

     A                         B                               C                                D