There are eight tips in Dr.Roger's lecture on sleep，and one of them is： to bed early unless you think it is necessary.
A. doesn't go
B. not to go
C. not going
D. don't go
网友回答
A. doesn't go
B. not to go
C. not going
(答案→)D. don't go
解析：考查特殊句式。句意：在Roger博士关于睡眠的讲座里面共有八点忠告，其中之一是：除非你认为有必要，否则不要太早上床睡觉。分析句子结构可知，冒号后的句子是一个祈使句，故选D项。