Question

是I think do sth. 还是I think doing sth.

Answer 1

应该是 think doing sth. 这是个短语. 但是都是 think about doing sth. 是打算做某事
想要做某事是：want to do sth.和 would like to do sth. 或者 feel like doing sth.

Answer 2

doing
think是动词 后面接宾语要用动名词形式 就是doing
如果你是要表达想做某事 应该用 i want to do sth

Answer 3

think 是不及物动词，其后通常不直接加动词。通常构成的短语有think about/of,或者后面接宾语从句。
其后不接动词的-ing形式，如果要用的话也是加to不定式，意思是记得，想起。。。
eg：I didn't think to tell her. 我没有想到要告诉她。
望采纳呀～