Do you know the kid with Bob is talking over there? — Yes, it’s my cousin.

This is book.

Mark Twain it famous ______ a writer ______ writing short stories.[ ]

I wonder ________ you’ll water this kind of flower.—Once a week.

This is 3-D printer. And this is an artificial (人工的) ear. Can you believe that scientists printed this artificial ear by this 3-D printer?