根据下面短文大意，用所给动词的正确形式填空。
Dark black clouds in a dull sky meant one thing and one thing only：there 1 （be）a thunderstorm．None of us 2 （bring）an umbrella，or even a raincoat，so when Jack suggested we 3 （go）to a museum，we all aGREed immediately．As we 4 （shop）all morning and 5 （now feel）very tired，it 6 （be）a pleasure 7 （sit down）．We took a bus and arrived just as large drops of rain 8 （begin，fall）．
The museum 9 （desert）and very peaceful．We sat down in the main hall and listened to the rain 10 （beat）against the windows．Suddenly there was a GREat disturbance at the entrance．Then some schoolboys 11 （lead in）by a teacher．The poor man 12 （try，keep）them quiet and threatening 13 （punish） them，but they did not pay the slightest attention．The boys ran here and there like a wild tribe（部落）． 14 （apologize） for this lack ofdiscipline（纪律），the teacher explained that they were 15 （rather excite）．But in the end the noise proved too much for us and we decided 16 （leave）．As Jack remarked when we 17 （walk）in the rain，the boys had more right 18 （be）in the museum than we had．After all，they 19 （come）on an educational visit，while we 20 （simply want）to get out of the rain．
key: 1．was going to be 2．had brought 3.（should）go 4．had been shopping 5．were now feeling 6．would be 7. to sit down 8．was beginning to fall 9．was deserted 10．beating 11．were led in 12．was trying to keep 13．to punish 14．Apologizing 15．rather excited 16．to leave 17．were walking 18．to be 19．had come 20．had simply wanted
