请看下面一道题：

If a book is in English, _________ means slow progress for you.A. as                      B. which                      C. what                       D. that
【分析】此题容易误选 A或B，想当然地根据空格前的逗号认为这是非限制性定语从句。这样分析的同学，主要是忽略了前一句句首的 if。其实此题应选D，逗号前是一个条件状语从句，逗号后是该状语从句的主句，that 在此代表前文所述的意思，用作主句的主语。同样地，下面几题也应选 that，而不选 which：

which(1) If he’s only interested in your looks, _________ just shows how shallow he is.A. as                        B. which                        C. what                       D. that(2) If you want to go, _________is quite all right with me. A. that                      B. which                        C. and it                      D. so(3) When I say two hours, _________ includes time for eating. A. as                        B. which                        C. what                       D. that(4) If you want a double room , _________ will cost another ￡15. A. as                    &nbew sp;   B. which                        C.  what                      D. that(5) If you have the money, _________ will be OK.A. as                        B. which                        C. and it                      D. that
下例也选 that 而不选 which，其中 that 表示“那”：

Unless I’m very much mistaken, _________ is my watch you’re wearing! A. as                        B. which                        C. what                        D. that