棉铃虫在卵发生期释放赤眼蜂进行生物防治,一般需连续放()次,每次放蜂每公顷1.5万~2万头。 ["1~2","2~3","3~4","4~5"]
用万用表测量电容器的电阻时()。 ["A、先将电容器进行放电,以免万用表烧坏","B、电容器在工作中可以测量","C、必须停止电容器充电回路,然后测量","D、可以用电压档测量"]
哪个不属于丑角八打戏?() ["A、“打花鼓”","B、“打樱桃”","C、“打杠子”","D、打酒馆"]
用赤眼蜂生物防治玉米螟缺点是防治效果受()因素影响大,天气干旱和风雨天会降低防治效果。 ["温度","湿度","气候","光照"]
《法门寺》中赵廉演唱的“眉坞县”是() ["A、二黄原板转快板","B、西皮慢板转二六","C、反二黄原板转散板","D、西皮二六转流水"]
按功能分,SDH的四种网络单元是()、()、()和()。