The old man was lying on the ground, ______ dead.

The little boy wishes to be ___.

—Did she say something in the lecture that _____you? ---Not really. Actually I felt sleepy over his speech.

Carbon dioxide, which makes a ______ between us and the sun, prevents heat from getting out of the atmosphere easily, so the earth is becoming warmer.

Professor Li preferred _______ lectures to his students to _______ to meetings on scientific developments.