The math problem is so hard. I really don’t know （ ）.
A.正确答案Cwhat to do it
B.how to do
C.how to do it
D.what do it
The math problem is so hard. I really don’t know （ ）.
The math problem is so hard. I really don’t know （ ）.
A.正确答案Cwhat to do it
B.how to do
C.how to do it
D.what do it
