Thesethreecollegestudentsarerealheroesbecausetheyrisked______theirownlivesinordertosavethedrowningboysinthewater.
A.havinglostB:toloseC.losingD.oflosing
是riskdoing形式,为啥选a不行,不是过去发生的事吗
邮箱:联系方式: