英语的问题请详细回答,说明理由...最好分的细点.好的话有追加哦...

英语的问题请详细回答,说明理由...最好分的细点.好的话有追加哦...
1.In ______Sahara Desert,_____rain was scarce,but in my hometown there is ______heavy rain now and then,and the river around the town rises a lot after_____.
A.the,the,a,a heavy rain B.the,,a,heavy rains
(为什么选B不选A?)
2.The building was completed in______ September of 1956 not in_____ October ,1955.
A., B.the, (为什么选B不选A?)
3.---Which share is meant for me?
----You can take ____ half.They're exactly the same.
A.each B.either (为什么选不选A?)
1.下列说法不正确的是( )
A.等质量的O2和O3含氧原子数相等
B.等质量的N2O4含氧原子数相等
C.等质量的SO2和SO3含氧原子数之比为2:3
D.等质量的NaOH和Ca(OH)2所含OH-离子的个数比为37:40
2.已知一个12C原子的质量为a(g),一个R原子的质量为b(g),N表示阿伏加德罗常数,则R的摩尔质量可表示为_______或_____.
3.含铁元素相等的FeO,Fe2O3,Fe3O4三种物质的物质的量之比为______,物质的质量之比为_____.
摩尔质量等的知识点回答,]