【单选题】在酸性溶液中与硫氰酸盐生成红色的方法 可用于检查的杂质为
【单选题】To obtain better steering control when you are towing alongside,your vessel should be positioned with its ().
A.
Bow extending forward of the tow
B.
Stern amidships of the tow
C.
Stern extending aft of the tow
D.
Bow even with the bow of the tow
【单选题】配制 pH≈5 的缓冲溶液,应选择下列哪组缓冲对 ( )
A.
NaH 2 PO 4 —Na 2 H PO 4 (pKa = 7.21)
B.
HAc—NaAc ( pKa = 4.75)
C.
NH 3 ∙H 2 O—NH 4 C1 ( pKa = 4.75)
D.
NaHCO 3 —Na 2 CO 3 ( pKa = l 0.25)
【单选题】在酸性溶液中与硫氰酸盐生成红色的方法可用于检查
【单选题】The child is ______ young to dress himself.