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;
B:checked
C:checking
D:to checking;
正确答案是:
同类题型
149. We won’t have _____ without your help.
I can’t go out to play because I ______my homework yet.
It was decided to _______ the search when there was no hope of finding the missing child alive.
It was silly __________ me to lose my underground ticket.
It seemed only several minutes _______ hefinished this painting .