一般天然香豆素类成分在其7位常有取代基,大多为( )
A.-OCH3B.-CH3C.-OHD.-COOHE.-CH2-CH3
参考答案:C
解析:[知识点] 香豆衰的结构
Children at the beginning of last century were ______to the life without television.
[ ]
A. disappointed
B. accustomed
C. puzzled
D. harmful
远视力检查采用国际标准视力表或对数视力表,对不会指认的儿童采用图形视力表。