2 . And up until maybe 5 or 10 years ago, the number of English­language recipes for Chinese dishes you could find in a cookbook or on the Internet ________________ (be) still extremely limited. (所给词的适当形式填空)

3 . Much of the world’s electronic waste will not be recycled, reused or even disposed of in a safe and controlled manner. Only around 17.5 percent ________________ (record) as recycled in 2019. （所给词的适当形式填空）

6 . So far, through the remote video monitoring system and the use of BDS and other equipment, the intelligent and information­based three­dimension system of the “sky and ground” for biodiversity protection ________________ (establish). （所给词的适当形式填空）

7 . Fountain pens ________________ (use) in schools long ago and have been regaining popularity lately because they are refillable. （所给词的适当形式填空）

8 . Investigating the way that dragonflies remain stable during flight actually ________________ (reveal) the techniques they use to get themselves out of tricky situations. (所给词的适当形式填空)