How can you _____ these two books apart?[ ]

Do you know the ________ “I am a singer”—Yes, I usually watch it on Friday.

— Are you still very busy? — Yes, I _____ the report for the manager and it won’t take long.[ ]

There are some dangerous fishes in this river, and I’ve warned Tom here.

The world____the greatest changes in China since China started thereform[ ]