【单选题】She used to ______ a bike to school, but now she is used to ______ to school. A. ride; walk B. riding; walking C. ride; walking
【单选题】铁盐检查时,需加入过硫酸铵固体适量的目的在于
A.
将高价态铁离子(Fe3+)还原为低价态铁离子(Fe2+)
D.
将低价态铁离子(Fe2+)氧化为高价态铁离子(Fe3+),同时防止硫氰酸铁在光线作用下,发生还原或分解反应而褪色
【多选题】铁盐检查时,加入过硫酸铵固体适量的目的是( )
【单选题】NaOH 溶液标签上标示的浓度为0.300mol/L,该溶液从空气中吸收了少量的CO2 ,现以酚酞为指示剂,用标准HCl溶液标定,标定结果比标签上标示的浓度( )。
【单选题】Multimodal transport refers to a transport system usually operated by a carrier with more than one mode of transport under the control or ownership of one operator. ( )
【简答题】Multimodal transport is obviously( )than segmented transport.
【单选题】Multimodal transport is a transport system for carriage of goods by at least ( ) different modes of transport.
【单选题】下列五种内服药品中,应在餐前服用的药物是
【单选题】铁盐检查时,需加入过硫酸铵固体适量的目的在于
D.
将低价态铁离子(Fe2+)氧化为高价态铁离子(Fe3+),同时防止硫氰酸铁在光线作用下,发生还原或分解反应而褪色
E.
将高价态铁离子(Fe3+)还原为低价态铁离子(Fe2+)
【单选题】如在乙醇溶液的瓶标签上写的浓度为“10→100”则表示( )。