全球可被人类利用的淡水总量仅占地球上总水量的0.00003，因此珍惜水、保护水是我们每一位公民义不容辞的责任，其中数字0.00003用科学记数法表示为[ ]

A.3×10^-4

B.3×10^-5

C.0.3×10^-4

D.0.3×10^-5

( ) In medieval times, an agree-upon “common tongue” came into use in the eastern Mediterranean ports, which was called Lingua Franca.The term lingua franca cannot be generalized to other languages similarly used.Thus, not any language can be a lingua franca.