【单选题】下列有效数字位数错误的是()。
A.
[H + ]=6.3×10 -12 mol/L(2位)
C.
c HCl =0.02502mol/L(4位)
【单选题】若在庭院空间中,各个主要视点景观所得的视角比值都大于()则将在心理上产生紧迫和闭塞感。
【单选题】Larry asks Bill and Peter to go on a picnic with him,but________of them wants to,because they have work to do. (2012·新课标全国,31)
【简答题】Bill wants to know whether ____________ has finished her paper.