第一节：单选填空（共15小题；每小题，满分15分）
21. With the aid of the most advanced equipment, new facts about the ancient pyramids in Egypt
have recently .
A. brought to light B. seen the light C. thrown light upon D. come to light
22. The project my students are working is quite challenging because it involves many
professional skills.
A. for which B. on which C. of which D. at which
