问题
选择题
______ he was exercising at the park yesterday morning, he found a purse under the tree.
A. While B. Before C. Though
答案
答案：A
题目分析：句意：昨天早晨，当他正在公园锻炼的时候，他发现树下有一个钱包。分析选项：while当……时候；before之前；though虽然。联系句意为当……时候。故选 A