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