Mr Green is an Englishman. He teaches English well His English classes are very interesting. He likes us and we like him, too.
Mr Green has two children----Mike and Nancy. Mike is eight and his sister Nancy is five. Mike goes to school but Nancy doesn't. Mr Green likes to wear a T-shirt and a pair of jeans. Football is his favorite sport. After school we often have a basketball match. Sometimes Mr Green watches and joins us. He plays basketball just for us.

己避免成为亡国之君，但最终还是失败。其主要原因是()