关于英语1.want to可以写成wanna,但wants to或wanted to可以吗?2.是have got to

关于英语
1.want to可以写成wanna,但wants to或wanted to可以吗?
2.是have got to还是got to可以写成gotta?
3.我觉得当get作系动词时,可以和be随意替换.（例：get broken/shot/sick...）
但是有几个我不太把握：you are as pretty as Carlos said.
A is 3 times longer than B.
I am 12 years old./I am 12.(这三个句子中的be可以与get替换吗?)