填空题 《复合题被拆开情况》 A pilot noticed a balloon which seemed to be【K1】________ (make) for a Royal Air Force Station nearby. He informed the station at once, but no one there【K2】________ (be) able to explain the mystery. The officer in the control tower was very angry when he heard the news, because balloons can be a great【K3】________ (dangerous) to aircraft. He said that someone might be spying on the station and the pilot was ordered to keep track【K4】________the strange object. The pilot managed【K5】________circle the balloon for some time. He could make out three men in a basket under it and one of them was holding a pair of binoculars. When the balloon was over the station, the pilot saw one of the men【K6】________ (take) photographs. Soon afterwards, the balloon began to descend and it landed near an airfield. The police were called in, but they could not arrest anyone, for the basket【K7】________(contain) two Members of Parliament and the Commanding Officer of the station! 【K8】________the Commanding Officer explained later, 【K9】________half of the station did not know【K10】________the other half was doing!《问题》：【K2】