题干
They have no idea at all ________.
A：where has he gone
B：where did he go
C：which place he has gone
D：where he has gone
答案(点此获取答案解析）
D
，它是由如下的A酸和B醇生成的一种酯，A酸结构简式为：
则 B醇的分子式为（ ）