The availability of calcium is highest in which of the following condition? A: The cation exchange capacity is 24 cmol(+)/Kg, while the exchangeable calcium is 12 cmol(+)/Kg B: The cation exchange capacity is 30 cmol(+)/Kg, while the exchangeable calcium is 8 cmol(+)/Kg C: The cation exchange capacity is 8 cmol(+)/Kg, while the exchangeable calcium is 5 cmol(+)/Kg D: The cation exchange capacity is 15 cmol(+)/Kg, while the exchangeable calcium is 6 cmol(+)/Kg

Alexis ______ her Canadian dollars for RMB before her trip to Beijing. A: exchange B: exchanged C: exchanging D: exchangeable

If [G,*] is a group, then * is() A: Satisfied combination law B: Have Unit element C: Every unit has inverse element D: Exchangeable

EXIF信息（Exchangeable Image File），它是记录在（）中的一组参数。 A: A图像 B: B场景描述 C: C数码照片 D: D主题