Many students are ________ chatting online, which wastes them plenty of time.
—Can you keep an eye on my bag? I need to go to the washing closet. — __________. It'll be safe with me.
—What a noise! I can hardly stand it. —It __________ as if they are having a party next door.
—But I don't know how to play the piano. — __________.
He tried his best to solve the problem, __________ difficult it was.
__________ private cars are bringing us convenience, they may also cause more traffic accidents and pollution.