【单选题】None of us knows which floor _______ on.
【单选题】_________ of us knows how many of them have been killed in that accident.
【简答题】水泥的水化热高不利于 施工。(提示:填春季、夏季、秋季或冬季,任选一)
【单选题】None of us knows _______ these new parts can be bought.
【单选题】心搏停止后,必须建立有效人工循环的时限为
【简答题】None of us knows how to _________ ( 操作 ) this new machine, so we’d better ask an expert first.