单项选择题
A.Variable B.Changing C.Backing D.Veering
The() is a smaller valve fitted in the auxiliary steam ...
单项选择题The() is a smaller valve fitted in the auxiliary steam supply line, and is usually of the non-return type.
A.main stem stop valve B.auxiliary steam stop valve C.feed check or control valve D.blow down valve
种子干燥时可采用日晒法的是()。A.松类种子B.栎类种子C.肉质果类种子D.特小粒种子
单项选择题种子干燥时可采用日晒法的是()。
应在生理成熟后形态成熟前采种的是()。A.生理后熟的种子B.缩短深休眠种子的休眠期C.短期休眠的种子
单项选择题应在生理成熟后形态成熟前采种的是()。