_______ fun I have playing computer games !
—You can hardly imagine the pleasure of chatting with friends on Wechat (微信).—Really? But it ______ cause you much trouble if someone get your personal information.
_________, when Marx was already ________, he began to learn Russian.
He made a serious mistake, but he took action to change that _________ it got worse.
We should try our best to make ______ world that is safer, cleaner and healthier than ____ one we are living in now.
—Hey, Tom. Let's go swimming.—Just a moment. I______ a message.