我国南方为害较重的蝼蛄是() ["东方蝼蛄","华北蝼蛄","普通蝼蛄","台湾蝼蛄"]
蛴螬的食性为() ["植食性","腐食性","杂食性","肉食性"]
我国为害农作物的主要地老虎类有() ["小地老虎","黄地老虎","八字纹地老虎","大地老虎"]
如何确定塑件的抽芯距?
气候因素中,影响蛴螬发生的关键因素是() ["温度","雨量","光照","气流"]
注射模塑成型时模具温度的影响因素较多,一般说来,在非结晶型塑料中溶体粘度低或中等粘度的塑料,模温可();对于熔体粘度高的塑料,模温可()。