这些英语句子错在了哪里

i have two brothers,both of them are teachers

i am not sure that shuold be declared

thanks for your help,i could pass the exams

i have two brothers,either of them is teacher（teacher在这里表示的是一种职业，没有复数）

i am not sure what should be declared

thanks to your help,i could pass the exams（thanks to的意思是由于 ，因为）

第一句和第三句除了i改成I之外好像没有错，第二句的从句里缺少主语

I am not sure that shuold be declared

这句话缺少主语。 should的拼写