母乳喂养应遵循的原则是（）
A.按时
B.按需
C.按量
D.按时按量
E.按时不按量
参考答案：B
— How clean and tidy your classroom is!
— Thank you. It ______ every day. [ ]
A. is cleaned
B. was cleaned
C. was cleaning
D. is cleaning
能治疗食积脘腹胀痛的药物是（）
A.苍术
B.莪术
C.莱菔子
D.延胡索
E.三棱
