下列句子中划线成语使用正确的一项是（    ）

阅读下面短文，掌握其大意，然后从所给的A、B、C和D项中，选出最佳选项。

    Animals United is a 3D German cartoon. Reinhard Klooss and Holger Tappe directed it. It is a story about animals.They get together to find 1. Along their journey, lots of funny things 2, and of course, they have a lot of adventures

    The animals in the grassland in Africa are 3 for coming flood. However, this year's flood seems to come later than in other years. The animals become unhappy and 4. At the same time, some animals from other places come to the grasslands to look for peace. However, the things are5 because the water is becoming less and less. 6 they decide to look for the river.

    Finally, they find the reason why they don't have any water to drink. People7a dam like a strong wall so that humans can have a better life. After a long fight with humans, they let the world know 8 that animals are in danger.

    This film is about environmental matters. The humans are the bad and the animals are the good. This film is to give humans a warning.They must not destroy the homes of animals or damage nature in order to9a better life. Humans should know that animals also have their own 10.

计算： ${\left(a-b\right)}^2-b\left(2a+b\right)=$ ____。

在等差数列$\left\{a_n\right\}$中，若$a_3+a_4+a_5+a_6+a_7=450$，则$a_2+a_8=$(   )