根据下列文章,请回答 21～25 题。 Text 1 An embarrassing experience It was the small hours of the morning when we reached London Airport. I had cabled London from Amsterdam, and there was a hired car to meet, but there was one more unfortunate happening before I reached my flat. In all my travels I have never, but for that once, been required by the British customs to open a single bag or to do more than state that I carried no goods liable to duty. It was, of course, my fault; the extreme tiredness and nervous tension of the journey had destroyed my diplomacy. I was, for whichever reason, so tired that I could hardly stand, and to the question,'have you read this?' I replied with extreme foolishness,'Yes, hundreds of times. ' 'And you have nothing to declare?' 'Nothing. ' 'How long have you been out of this country?' 'About three months. ' 'And during that time you have acquired nothing?' 'Nothing but what is on the list I have given you. ' He seemed momentarily at a loss, but then he attacked. The attack, when it came, was utterly unexpected. 'Where did you get that watch?' I could have kicked myself. Two days ago, When playing water games with a friend in the bath, I had forgotten to take off my ROLEX OYSTER, and it had, not unnaturally, stopped. I had gone into the market and bought, for twelve shillings and six pence, an ugly time piece that made a strange noise. It had stopped twice, without any reason, during the journey. I explained, but I had already lost face. I produced my own watch from a pocket, and added that I should be grateful if he would confiscate the replacement. 'It is not a question of confiscation,' he said, 'there is a fine for failing to declare dutiable goods. And now may I please examine that Rolex?' It took another quarter of an hour to persuade him that the Rolex was not contraband; then he began to search my luggage. 第 21 题 When did the writer arrive at London airport?