1.（2021 连云港）Yuan Longping, one of ____________（最伟大的科学家）, made important contributions to the world.
2.（2019 无锡）如果你能告诉我机器人已失控多久，那就太好了。
It would be great if you can tell me ____________.
3.（2018 连云港）— Have you met Luke recently?
— Yes, I ____________（碰巧看见他）in the science museum yesterday afternoon.
4.（2023 威海）昨天上午我到那儿的时候，很多人在看书。
____________

1. the greatest scientists
2. how long the robot has been out of control
3. happened to see him
4. Many people were reading when I got there last morning.