问题
We knock _____people’s doors, and they usually give us some candy ______ a treat.[ ]
A: on, to
B:, at, to
C: on, as
D:on, on
B:, at, to
C: on, as
D:on, on
正确答案是：
同类题型
Millie _________ a picture when Mr. Green came in.
More wild tigers have been seen in the forest around this area, ________ there used to be very few.
Where is Mr. Green now? I haven’t seen him for a few days —- He ________________ to Shanghai.
Do you know_______ this dictionary belongs to? -Let me see. Oh, it’s_______.