用所给词的适当形式填空。（必要时可加助动词或情态动词。）

     It's sometimes 1______ (report) that strange objects 2______ (see) high up in the sky. These unidentified

flying objects 3______ (make)a lot of people interested. Some of the reports about them are difficult 4______

(believe). Some have been explained in scientific ways, and others have never been explained.

     It's not easy to decide whether a report is true or not. One report of UFOs. 5______ (come) from a British

plane on its way from New York to London in 1954. The Brisith plane 6______ (fly) over an island at 19,000

feet when the captain 7______ (notice) that something was on their left and a little lower than their plane. It

was about five miles away.

     "It was not one object but several." The captain said. "Well 8______ (see)one large and six small objects. I

sent radio message to report about this and I received the answer that the other planes 9______ (come) out to

meet us. Before the planes arrived, the smaller objects entered the larger one. The large object then became

smaller and 10______ (move) away fast".