struggle for survival natural selection ,survival of the fittest是什么意思?

struggle for Struggle for my dream struggle for the Struggle for my life! Struggle for Love struggle for power/equal struggle against,struggle with 和 struggle for有什么区别? struggle for living怎么读 Will always struggle and the struggle for Wani. struggle struggle. .Struggle struggle struggle for the dream是啥意思 这句话struggle for life说的是什么意思? Efforts to the struggle for tomorrow They had to__all kinds of difficulties.A.struggle for B.struggle against C.struggle D.fight for Struggle for life,work hard for the future!