23. Please ask not to skate on the thin ice.It’s very dangerous. A. they B. them C. their

问题补充：

23. Please ask not to skate on the thin ice.It’s very dangerous.

A. they

B. them

C. their

D. Theirs

答案：

A. they

(答案→)B. them

C. their

D. Theirs

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