They have________signs in some places to remind (提醒)the visitors not to step on the grass.
Old McDonald gave up smoking for a while, but soon _____ to his old way.
What _____ to Joan last night? What did she cry for?
_____ is the population of your country?
Please say "Hi" to Bob ______ me.
After we walked ______ the forest, and ______ a river, we arrived at that small village.