1. (2021八上·兰溪月考) 用方框中所给单词或词组的适当形式填空，每词限用一次。

plant  crowded   twenty   million  about

1. （1） Every year, of tourists come to Beijing for holidays.
3. （2） Look, the playground is with many students playing games.
5. （3） Lu Xun is one of the greatest writers in the century in China.
7. （4） He got lost, his mother was worried  him .
9. （5） I think spring is the best timetrees.