The existence of many stars in the sky  lead  us to suspect that there may be life on another planet.

                  A                                                         B                                              C                 D    

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

        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 package must be wrapped carefully before it is post.

                 A                     B                                C           D

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

                                              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

Mark the letter A, B, C, or D to indicate the underlined part that needs correction in each of the following questions.

 They had visited Ho Chi Minh Mausoleum at this time last Sunday.

                     A                                       B        C                  D