麻烦各位，帮忙解释一下这道英语题，万分感谢

Question

i think that ______ lots of speaking practice is one of the secrets of becoming a good language learner.
A.do B.doing
C.does D.did

Answer 1

doing lots of speaking practice 在这里做宾语从句的里的主语;think后全部为宾语成分.

我认为大量的口语实践是成为一个优秀语言学习者的秘诀.

Answer 2

c

Answer 3

B,动名词做主语

Answer 4

I think that +从句（主+谓+宾）主语应为名词或动名词，do的动名词是doing．故选D

Answer 5

B doing是动名词做主语

Answer 6

B ” becoming a good”
此句为宾语从句 所以为doing