1. 用方框中所给单词或短语的适当形式填空

unknown   control   knock   talk to   talk   about

1. （1） He wanted to the aliens to find out how they came to Earth.
3. （2） Nancy wanted to the space travel in her class.
5. （3） The spaceship was trying to land on an planet.
7. （4） The captain wanted to find the strongest creature and it.
9. （5） The policeman the thief to the ground and arrested him.