①∵1km/h=
m/s,∴54km/h=54×1 3.6
m/s=15m/s;1 3.6
②300cm/min=300×
=300×0.01m 60s
m/s=0.05m/s;1 6000
③∵1dm=10cm,∴1.7dm=1.7×10cm=17cm;
∵1dm=102mm,∴1.7dm=1.7×102mm;
∵1dm=108nm,∴1.7dm=1.7×108nm;
∵1dm=105μm,∴1.7dm=1.7×105μm.
故答案为:15;0.05;17;1.7×102;1.7×108;1.7×105.