下列有关表面活性剂结构描述正确的是
A. 表面活性剂分子一般由极性烃链和一个以上的非极性基团组成
B. 极性基团只可能是离子基团
C. 烃链长度在6个碳原子以上
D. 极性基团可以是碳酸及其盐
E. 脂肪酸类表活性剂(R-COO-)中，R-为亲油基团
某片剂标示量为100g，测得颗粒剂中主药含量50%，则每片颗粒重
A. 300rug
B. 200mg
C. 150mg
D. 100mg
E. 50mg
How can a mother help the baby to cry less
A. Cuddle the baby until he is quiet.
B. Leave the baby alone.
C. Do not always attend to the baby.
D. Teach the baby not to cry.
From the first paragraph we know that ______.
A. mother care is the best according to a national study
B. child care outside home is the best in accordance with the study
C. regular child care outside home may play a role as a mother
D. connections between mothers and infants are damaged by outside care
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