1 . 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)

2 . 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）

3 . Suzhou, considered by the Italian explorer Marco Polo in the 13th century as “the Venice of the East”, became a sister city to Venice in 1980, and since then multiple activities of mutual historical and cultural exchange ________________ (carry) forward. (所给词的适当形式填空)

4 . I am sure you know something about Tai Chi. The fluid combination of slow, graceful movements and lightning­quick strikes easily ________________ (set) Tai Chi apart from other martial arts. （所给词的适当形式填空）

5 . 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）

6 . 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）

7 . 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)

8 . Breathing dirty air causes the premature death of at least 1,200 children across Europe each year. Actually, many thousands more ________________ (trouble) with physical and mental health problems that could have lifelong impacts. （所给词的适当形式填空）

9 . By the end of the expedition, we ________________ (climb) 12 mountains, watched 108 nest boxes, tagged 35 mammals, banded 74 birds and measured more than a thousand trees. We were tired out... (所给词的适当形式填空)

10 . These beautiful black­faced spoonbills are some of the world's rarest birds. The birds ________________ (fly) all the way from their summer home to this wetland, where they will spend the winter. Now, they circle and land. （所给词的适当形式填空）