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It's sometimes reported that strange objects have been seen high up in the sky. These unidentified(未确认的) flying objects - UFOs have made a lot of people interested. Some of the reports about them are difficult to believe.Some have been explained in scientific ways, others have never been explained.

　　It is not easy to decide whether a report is true or not. One report of UFOs came from a British plane on its way from New York to London in 1954. The British plane was flying over an island at 19,000 feet when the captain noticed that something was on their left and a little lower than their plane. It's about five miles away.

　　"It was not one object but several," the captain said. "We saw one large and six smaller objects. I sent a radio to report about them and I received the answer that the other planes were coming out to meet us. Before the planes arrived, the smaller objects entered the big objects. The big object then became smaller and moved away fast."

1.Some_____ have been explained in scientific ways.

2. In 1954, a British plane met a UFO when it was flying from_____ to_____.

3. The captain_____ and saw something on the left of their plane.

4. How many objects did the captain see?

5. The big object moved away because_____.