手机铃声-雨宝咒:高手帮帮忙

来源:百度文库 编辑:高校问答 时间:2024/07/06 00:12:02
12. He spent the whole morning _____ to solve the math problem.[ 1分]
A.to try B.trying C.having tried D.being tried

B
spend doing sth.