A.30倍 B.20倍 C.15倍 D.10倍
A.21個(gè)月;75% B.23個(gè)月;80% C.25個(gè)月;85% D.27個(gè)月;90%
A.24個(gè)月 B.18個(gè)月 C.12個(gè)月 D.6個(gè)月