用方框中所给单词的适当形式填空。

1. China has developed _______________ in recent years. (rapid)

2. The problem kids in the Hall has given Zack a good chance to ______________. (success)

3. An SOS Children's Village gives helps to the _____________ people. (home)

4. A large population causes many ______________ in India. (difficult)

5. My uncle ______________ in Beijing for more than twenty years. (work)

数列{a_n}是等差数列，S_n是其前n项和，有且S₇＜S₈，S₈=S₉＞S₁₀，则在下列结论中错误的是（　　）

A．a₉=0

B．d＜0

C．S₁₁＞S₇

D．S₈与S₉均为S_n的最大值