复种的例子 年两熟( double cropping): Winter wheat- summer maize 年三熟( triple cropping): Canola- early rice- late rice 二年三熟( three harvests in two years) Spring maize- winter wheat- summer sweet potato复种的例子 一年两熟（double cropping）： Winter wheat - summer maize 一年三熟（triple cropping）： Canola - early rice – late rice 二年三熟（three harvests in two years）： Spring maize → winter wheat – summer sweet potato