强调句还是状语从句

强调句还是状语从句
 
这道题是考查强调句还是状语从句？仔细看看：
—Was it under the tree _____ you were away talking to a friend? http://yingyu.chazidian.com
—Sure. But when I got back there, the bike was gone.
A. that                            B. where
C. which                        D. while
【陷阱】此题很容易误选A，认为这是强调句型。
【分析】其实此题应选D。做好此题的关键是正确理解上下文的语境。在此句中，it 是代词，指代 the bike，句意为：“当你离开去同朋友谈话的时候，你的自行车是在这树下吗?”“当然，但当我回来时，自行车就不见了。”现在反过来分析一下，假若选A，将此句判为强调句，句子即为 Was it under the tree that you were away talking to a friend? 若进一步转换为非强调句，句子则为 Under the tree while you were talking to a friend，句意显然很荒唐。