爬取狮城bbs困扰了我一天的Python基础题

 

结果在爱球球大哥的帮助下成功解决，代码如下

a = ["2.5", "2.4", "2.9", "3.5"]
b = ["-", "*", "-"]

finally_str = ""
for i in range(len(a)):
    finally_str = finally_str + a[i]
    finally_str = str(eval(finally_str))
    print(finally_str)
    try:
        finally_str = finally_str + b[i]
        print(finally_str)
    except Exception:
        break

print(finally_str)