I won't sleep well if(I don't read)in bed for half an hour.a.I'm not reading b.I don't read c. I didn't read d. I wasn't reading这里为什么选B?其他三项为什么不行呢?请帮忙分析一下,有点混乱. .

I won't sleep well if(I don't read)in bed for half an hour.a.I'm not reading b.I don't read c. I didn't read d. I wasn't reading这里为什么选B?其他三项为什么不行呢?请帮忙分析一下,有点混乱. .
I won't sleep well if(I don't read)in bed for half an hour.
a.I'm not reading b.I don't read c. I didn't read d. I wasn't reading
这里为什么选B?其他三项为什么不行呢?请帮忙分析一下,有点混乱. .

I won't sleep well if(I don't read)in bed for half an hour.a.I'm not reading b.I don't read c. I didn't read d. I wasn't reading这里为什么选B?其他三项为什么不行呢?请帮忙分析一下,有点混乱. .
因为依内容分析,此句型是属於下列的型态4,『现在或未来可能发生的状况』,所以要选B.
1.与现在事实相反
If+S+过去式动词,S+would(could ,should,might)+原型动词
例如:If I were rich,I would help you.
因为现在我不有钱,所以是与现在事实相反的用法
2.与过去事实相反
If+S+过去完成式,S+would(could ,should,might)+have+p.p
例如:If he had told me the truth,I would not have made the mistake.
因为已经是过去的事了,所以假设句一律用完成式
3.与未来事实相反
表示对未来事情的假设,实际上绝不可能发生.
If+S+were to +V,S+would(could,should,might)+原型动词
例如:If we were to live to be 200 years old,we could change everything.
4.现在或未来可能发生的状况
If+S+现在式动词,S+ 祈使句 或 will(can,may,shall )+原型动词
例如:If it rains tomorrow,I shall not go.