______ is very difficult.
— How can I wake up early? — Set the alarm (闹铃) at 5 o’clock, ________ you’ll make it.
——Do you know _____A/H1N1 disease? ——Yes, we should have a good habit about health.
They were_______ busy_______ with each other__________the time.
—What do you______ the TV series? —It is_____. I’ve never seen such a better one before.
China, ____ one of the great four countries with ancient civilizations, is best-known _______ its great development in all the fields over the years.