正常情况下，将成熟的花粉粒离体培养成单倍体植株幼苗时，细胞内不可能出现的是

把$a\sqrt{-\frac{1}{a}}$的根号外的因式移入根号内得 (     )

用轻质的细线将4N的物体系在标有3V0.5W的小电动机上，当小电动机接在3V的电源上时，10s内将物体提升了1m，关于该过程，下列说法错误的是(  )

    Many people like spring, because they can go out and do many kinds of activities. We made a survey about the activities that people like to do in spring. Here are the results.
Scott：
    In spring, I often visit my uncle and I like fishing with him. I also like boating and enjoy the beach. Last spring my uncle and I went boating. The dolphins came so close to us. It was very amazing. I hope that I can go there again soon.
Linda:
    My favorite spring activity is gardening (园艺). I think it is relaxing to work in the garden. I grow many flowers in my garden every year. They are so beautiful.
Nancy：
    I love spring. I love going to the beach and spending a whole day there. It is so relaxing to lie on the beach. I also like surfing in the sea.
James：
    I am twelve years old. My favorite spring activity is swimming. I started to learn swimming when I was seven years old. I always have a good time with my friends in the river.

These are m____ coats.