which引导非限定性定语从句时谓语用单数还是复数

如果which在从中做主语看先行词,先行词是单数谓语三单,先行词复数谓语复数,如果which修饰整个句子,一般用单数She is an artist,which I am not.她是一位艺术家,而我不是.Water,which is a clear liquid,has many uses.水是一种清澈的液体,有许多用途.The two policemen were completely trusted,which in fact they were.那两个警察完全受到信任,事实上,也真是如此.② which指代主句中的形容词.如：She was very patient towards the children,which her husband seldom was.她对孩子们很耐心,她丈夫却很少这样.She is always careless,which we should not be.她总是马虎大意,我们可不应该这样.③ which指代主句中的某个从句.如：He said that he had never seen her before,which was not true.他说以前从没见过她,这不是真的.④ which指代整个主句.如：In the presence of so many people he was little tense,which was understandable.在那么多人面前他有点紧张,这是可以理解的.He may have acute appendicitis,in which case he will have to be operated on