1. Polyploids can arise by somatic doubling, by the fusion of unreduced gametes, and by means of a triploid bridge. 多倍体产生与体细胞染色体的加倍、未减数配子的融合以及一种叫三倍体桥的方法。
2. Show that doubling the transmission frequency or doubling the distance between transmitting antenna and receiving antenna attenuates the power received by 6 dB. 证明：当传输频率增加一倍或者源天线与目的天线的距离增加一倍时，衰减功率等于6分贝。
3. The screen is divided into halves, and each half is scanned simultaneously, thereby doubling the number of lines refreshed per second and providing a sharper appearance. 萤幕被分成两半，并且一半每一个被同时扫描，因此使加倍线的数量每秒和提供一个骗子恢复精神外表。
英英解释
n.
1. increase by a factor of two
2. raising the stakes in a card game by a factor of 2
