The little monkey is very excited ____ to the zoo.
His speech was so _________ that it makes me feel _________.
—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.