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".
