we / to express / take / of your help / our sincere / this opportunity / appreciation
【正确答案】：We take this opportunity to express our sincere appreciation of your help.
【题目解析】：句意为我们借此机会向您表示衷心的感谢。take opportunity to do sth.意为”抓住机会干某事“；express one's sincere appreciation意为”表示衷心的感谢“。
