Coal was formed out of dead forests by chemical ______ .
The color green in ancient Egypt symbolized spring, which is the time of _______ year when things in nature start to grow after _______ long winter.
—Do you mind if I record your lecture?—_______.
This is one of the best novels _______ appeared this year.
President Obama made a speech for half an hour without his notes.
Look at the timetable. Hurry up! Flight 4026 off at 18:20.