—Glad to meet you. —____________
18. I used to be a very delighted girl. I guess no human being could have passed _______ childhood.
17. The new outline will throw light _______ students’ understanding of history.
--- Well, Linda, I’m sorry but I have to leave.--- _______. I hope to hear from you soon.
15. Researchers _______ to develop vaccines and this will probably take several months to complete.
14. Water can absorb and give off a lot of heat, thus ________ a stable environment.