【单选题】在正常情况下不能通过滤过膜的物质是
A.
Na + 、 K + 、 Cl − 等电解质
【单选题】— Do you want to study in the famous research institute? — Of course, anyone that _______ be chosen may be lucky. [ ]
【简答题】设当x=θ时,函数f(x)=sinx-2cosx取得最大值,则cosθ=______.
【简答题】设当x=θ时,函数f(x)=sinx-2cosx取得最大值,则cosθ=______
【单选题】An unhappy childhood may have some negative effects on a person's character; however, they are not always ________. [ ]
【单选题】测定下列金属污染物,水样保存时不能加酸酸化的是 。A. Pb2+ B. Cd2+ C. Cr6+ D. Hg2+