In summer milk will quickly go bad_____ it is put into a fridge.
— I wonder if I can learn English well.— _______. All things are difficult before they are easy.
— I missed the beginning of The Voice of China yesterday evening.—_________! But you can watch the re-play tonight.
What method can you think of _________ with these broken computers?
Scientists are trying their best to_______ ways to treat the terrible disease caused by Ebola(埃博拉).
—The air pollution is terrible.— It will be worse ________ we take action to protect the environment.