根据句意及首字母提示，写出可替代句中下划线部分的短语。

小题1:We will be not friends any longer if you copy my homework.  n　　　　　　

小题2:Lillian worries about her daughter when she is away, even though she has been old enough to take care of herself.   l　　　　　　

小题3:Linda kept a notebook with her in order to put down everything interesting she thought of.  w　　　　　　

小题4:They went to bed late last night playing online games. s　　　　　　

小题5:Now, many middle school students have fallen into a bad habit — smoking. A　　　　　　

从根本上说，（）是科技论文科学性的保证。

A.实践性和理论性

B.科学态度和科学精神

C.正确的理论研究

D.科学性的选题