A mechanical system in which the movement of the back roller is required to supply the energy to effect an alteration in the rate of rotation of the beam can never be perfect. 利用机械装置使后梁为织轴提供改变运转速率的动能,效果绝对不会理想。
Under natural conditions, seed germination due to lack of nutrients required to coexist with the fungus, for the supply of nutrients to complete germination, the germination rate is very low. 在自然条件下,种子萌发因缺乏营养物质,需与真菌共生,以获得养分的供给才能完成萌发,发芽率极低。