1 . 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)

2 . 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）

3 . 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）

4 . 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)

5 . 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 . 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）

10 . Not only are tea-­related customs found across the country, but also they ________________ (influence) the rest of the world since ancient times through the ancient Silk Road and trade routes. （所给词的适当形式填空）