单词百变屋
⑴A: What does this sign mean?
B: It means we ________ (should) walk on the grass.
⑵A: What does that ________(sign) mean?
B:It ________(mean) we shouldn't ________(littering)．
⑶A: What ________ (do) these ________(sign) on the wall ________(mean)?
B: They ________(mean) we ________ (should) take photos.