Secondary and higher education _____ available to all high school graduates in this country so far.
17. The boy sat at the top of the hill, looking at the valley ______.
16. I have never heard such a beautiful song _____.
15. With the development of West China, many technicians are _____ needed there in recent years.
14. China has a lot of coal and oil, and it is rich in other rare minerals ______.
13. --- How long has he been in the army?--- Oh, he joined the army as far ____ as 1997.