化学： V2O3和V2O5按不同物质的量之比混合可按计量完全反应，今欲制备V8O17，则V2O3与V2O5的物质的量之比应为：_______
由Co2.H2,和CO组成的混合气体在同温同压下与N2的密度相同，则该混合气体中CO2、H2和CO体积之比为 _________
实验常用98%（d=1.84g/ml)的浓H2SO4配制1:4的稀H2SO4。此稀H2SO4的密度为1.23g/ml,则该物质的量浓度为： _________
生物：
一个由200个碱基对构成的DNA分子，可能的碱基排列顺序有多少种
一定要告诉我算法
英语：
The train ____ she was traveling was late.
A which B. where C. on which D in that.
This is the hotel _____ last month.
A. which they stayed B at that they stayed C where they stayed at D. where there stayed
The factory ______ we'll visit next week is not far from here.
A.where B.to which C.which D in which
Li Ming ______ to the concert enjoyed it very much.
A. I went with B. with whom I went. C.with who I went D. I went with him.
另外告诉我which的用法。 比如in which to which for which by which 等等。