一等水准测量,基辅分划所测高差之差,不得超过() ["A、±0.7mm","B、±0.5mm","C、±0.4mm"]
浮游植物定量一般使用()ml计数框。 ["A、0.01","B、0.1","C、1","D、10"]
生物进化的基本单位是()。 ["个体","群落","种群","生态系统"]
一等水准测量,基辅分划读数差,不得超过() ["A、±0.7mm","B、±0.5mm","C、±0.3mm"]
目前我国直读电工测量仪表按照准确度分为()级。 ["七;","五;","十;","十二。"]
为何要设置非常溢洪道?