如图是家庭电路，从图中看出灯泡和插座上的用电器是____联，灯泡的开关接在火线与灯泡之间是为了____。

Did you help the farmers with the rice ____(丰收) last year?

分子式为C₅H₁₀属于烯烃的同分异构体有（包括顺反异构）

下列关于种群、群落和生态系统的描述，不正确的是（    ）

Tom accumulated a grate deal of knowledge about plants and agriculture in growing strawberries, he went back to the abandoned          of spreading straw under the fruit to reduce the necessary amount of watering.