The robot needs _______ once a month. An
题型:选择题
问题:
The robot needs _______ once a month. And we will check it for you for free.
A.to check
B.checked
C.checking
D.to checking
The robot needs _______ once a month. And we will check it for you for free.
A.to check
B.checked
C.checking
D.to checking