一个商店把某种货物按标价的九折出售,仍可获利20%,该种货物的进价为每件21元,则每件货物的标价为[ ]
A.27.72元
B.28元
C.29.17元
D.30元
答案:B
—_____ will you play basketball with me?
—In about 20 minutes after finishing my homework.
A.How soon
B.How long
C.How often
D.How far
混凝土外加剂按其主要功能分为哪些?