Achieving a high degree of proficiency in English as a foreign language is not a mysterious _____ without scientific basis.
I don't know if you noticed their behaviors or not, but we______.
Here is the tower, ______ top you can have a good view of the whole city.
People in industrial countries take in as they actually need every day.
To meet the challenge, the young people preferred heavier work to do in their spare time.
--- What has happened to Alice ? --- I don’t know. She her job.