----Mum,we are going mountain climbing this afternoon.---! Sometimes they’ll roll down

----Mum,we are going mountain climbing this afternoon.
----- ! Sometimes they’ll roll down the hillside.
A. Watch your step
B. Watch out for stones
C. Sounds great
D. Have fun

A. Watch your step(答案→)B. Watch out for stonesC. Sounds greatD. Have fun解析：考查交际用语。A担心台阶；B注意石头；C听起来很棒；D玩的开心；句意：—妈妈，今天下午我们要去爬山。—注意石头。有时候他们会从山上滚下来的。根据句意说明B正确。

这个答案应该是对的