有甲、乙、丙三种货物,若购甲3件,乙7件,丙1件,共需315元;若购甲4件,乙10件,丙1件,共需420元.现在购买甲、乙、丙各1件,共需( )
A:105元
B:210元
C:170元
D:不能确定
What ____ (is/do) you hear?
培养细菌或真菌的正确操作步骤是( )
①接种 ②配制培养基 ③恒温培养 ④高温灭菌
Lucy hurried to school.She didn't have breakfast.(合并为一句)
Lucy hurried to school____ ____ .