二环系(second cycle line)
从自交系间杂交种中选育的自交系称为二环系。
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一环系(first cycle line)
二环系
什么叫玉米的一环系和二环系?
If there is another line already on the bollard ,the eye of the second line should be()before placing it over the bollard.A、taken up through the eye of the first lineB、taken up over the eye of the first lineC、made fast to the first lineD、taken up from the eye of the first line
The pilot ask () to throw a heaving line to lift his bag.A、chief officerB、captainC、the duty sailorD、the second officer
异附加系(alien addition line)